Provided by: condor_23.4.0+dfsg-1ubuntu4_amd64 
NAME
classads - HTCondor Manual
ClassAds are a flexible mechanism for representing the characteristics and constraints of
machines and jobs in the HTCondor system. ClassAds are used extensively in the HTCondor
system to represent jobs, resources, submitters and other HTCondor daemons. An
understanding of this mechanism is required to harness the full flexibility of the
HTCondor system.
A ClassAd is a set of uniquely named expressions. Each named expression is called an
attribute. The following shows ten attributes, a portion of an example ClassAd.
MyType = "Machine"
TargetType = "Job"
Machine = "froth.cs.wisc.edu"
Arch = "INTEL"
OpSys = "LINUX"
Disk = 35882
Memory = 128
KeyboardIdle = 173
LoadAvg = 0.1000
Requirements = TARGET.Owner=="smith" || LoadAvg<=0.3 && KeyboardIdle>15*60
ClassAd expressions look very much like expressions in C, and are composed of literals and
attribute references composed with operators and functions. The difference between ClassAd
expressions and C expressions arise from the fact that ClassAd expressions operate in a
much more dynamic environment. For example, an expression from a machine's ClassAd may
refer to an attribute in a job's ClassAd, such as TARGET.Owner in the above example. The
value and type of the attribute is not known until the expression is evaluated in an
environment which pairs a specific job ClassAd with the machine ClassAd.
ClassAd expressions handle these uncertainties by defining all operators to be total
operators, which means that they have well defined behavior regardless of supplied
operands. This functionality is provided through two distinguished values, UNDEFINED and
ERROR, and defining all operators so that they can operate on all possible values in the
ClassAd system. For example, the multiplication operator which usually only operates on
numbers, has a well defined behavior if supplied with values which are not meaningful to
multiply. Thus, the expression 10 * "A string" evaluates to the value ERROR. Most
operators are strict with respect to ERROR, which means that they evaluate to ERROR if any
of their operands are ERROR. Similarly, most operators are strict with respect to
UNDEFINED.
CLASSADS: OLD AND NEW
ClassAds have existed for quite some time in two forms: Old and New. Old ClassAds were the
original form and were used in HTCondor until HTCondor version 7.5.0. They were heavily
tied to the HTCondor development libraries. New ClassAds added new features and were
designed as a stand-alone library that could be used apart from HTCondor.
In HTCondor version 7.5.1, HTCondor switched to using the New ClassAd library for all use
of ClassAds within HTCondor. The library is placed into a compatibility mode so that
HTCondor 7.5.1 is still able to exchange ClassAds with older versions of HTCondor.
All user interaction with tools (such as condor_q) as well as output of tools is still
compatible with Old ClassAds. Before HTCondor version 7.5.1, New ClassAds were used only
in the Job Router. There are some syntax and behavior differences between Old and New
ClassAds, all of which should remain invisible to users of HTCondor.
A complete description of New ClassAds can be found at
http://htcondor.org/classad/classad.html, and in the ClassAd Language Reference Manual
found on that web page.
Some of the features of New ClassAds that are not in Old ClassAds are lists, nested
ClassAds, time values, and matching groups of ClassAds. HTCondor has avoided using these
features, as using them makes it difficult to interact with older versions of HTCondor.
But, users can start using them if they do not need to interact with versions of HTCondor
older than 7.5.1.
The syntax varies slightly between Old and New ClassAds. Here is an example ClassAd
presented in both forms. The Old form:
Foo = 3
Bar = "ab\"cd\ef"
Moo = Foo =!= Undefined
The New form:
[
Foo = 3;
Bar = "ab\"cd\\ef";
Moo = Foo isnt Undefined;
]
HTCondor will convert to and from Old ClassAd syntax as needed.
New ClassAd Attribute References
Expressions often refer to ClassAd attributes. These attribute references work differently
in Old ClassAds as compared with New ClassAds. In New ClassAds, an unscoped reference is
looked for only in the local ClassAd. An unscoped reference is an attribute that does not
have a MY. or TARGET. prefix. The local ClassAd may be described by an example.
Matchmaking uses two ClassAds: the job ClassAd and the machine ClassAd. The job ClassAd is
evaluated to see if it is a match for the machine ClassAd. The job ClassAd is the local
ClassAd. Therefore, in the Requirements attribute of the job ClassAd, any attribute
without the prefix TARGET. is looked up only in the job ClassAd. With New ClassAd
evaluation, the use of the prefix MY. is eliminated, as an unscoped reference can only
refer to the local ClassAd.
The MY. and TARGET. scoping prefixes only apply when evaluating an expression within the
context of two ClassAds. Two examples that exemplify this are matchmaking and machine
policy evaluation. When evaluating an expression within the context of a single ClassAd,
MY. and TARGET. are not defined. Using them within the context of a single ClassAd will
result in a value of Undefined. Two examples that exemplify evaluating an expression
within the context of a single ClassAd are during user job policy evaluation, and with the
-constraint option to command-line tools.
New ClassAds have no CurrentTime attribute. If needed, use the time() function instead. In
order to mimic Old ClassAd semantics in current versions of HTCondor, all ClassAds have an
implicit CurrentTime attribute, with a value of time().
In current versions of HTCondor, New ClassAds will mimic the evaluation behavior of Old
ClassAds. No configuration variables or submit description file contents should need to be
changed. To eliminate this behavior and use only the semantics of New ClassAds, set the
configuration variable STRICT_CLASSAD_EVALUATION to True. This permits testing expressions
to see if any adjustment is required, before a future version of HTCondor potentially
makes New ClassAds evaluation behavior the default or the only option.
CLASSAD SYNTAX
ClassAd expressions are formed by composing literals, attribute references and other
sub-expressions with operators and functions.
Composing Literals
Literals in the ClassAd language may be of integer, real, string, undefined or error
types. The syntax of these literals is as follows:
Integer
A sequence of continuous digits (i.e., [0-9]). Additionally, the keywords TRUE
and FALSE (case insensitive) are syntactic representations of the integers 1 and
0 respectively.
Real Two sequences of continuous digits separated by a period (i.e., [0-9]+.[0-9]+).
String A double quote character, followed by a list of characters terminated by a
double quote character. A backslash character inside the string causes the
following character to be considered as part of the string, irrespective of what
that character is.
Undefined
The keyword UNDEFINED (case insensitive) represents the UNDEFINED value.
Error The keyword ERROR (case insensitive) represents the ERROR value.
Attributes
Every expression in a ClassAd is named by an attribute name. Together, the
(name,expression) pair is called an attribute. An attribute may be referred to in other
expressions through its attribute name.
Attribute names are sequences of alphabetic characters, digits and underscores, and may
not begin with a digit. All characters in the name are significant, but case is not
significant. Thus, Memory, memory and MeMoRy all refer to the same attribute.
An attribute reference consists of the name of the attribute being referenced, and an
optional scope resolution prefix. The prefixes that may be used are MY. and TARGET.. The
case used for these prefixes is not significant. The semantics of supplying a prefix are
discussed in classads/classad-mechanism:classad evaluation semantics.
Expression Operators
The operators that may be used in ClassAd expressions are similar to those available in C.
The available operators and their relative precedence is shown in the following example:
- (unary negation) (high precedence)
* / %
+ - (addition, subtraction)
< <= >= >
== != =?= is =!= isnt
&&
|| (low precedence)
The operator with the highest precedence is the unary minus operator. The only operators
which are unfamiliar are the =?=, is, =!= and isnt operators, which are discussed in
classads/classad-mechanism:classad evaluation semantics.
Predefined Functions
Any ClassAd expression may utilize predefined functions. Function names are case
insensitive. Parameters to functions and a return value from a function may be typed (as
given) or not. Nested or recursive function calls are allowed.
Here are descriptions of each of these predefined functions. The possible types are the
same as itemized in classads/classad-mechanism:classad syntax. Where the type may be any
of these literal types, it is called out as AnyType. Where the type is Integer, but only
returns the value 1 or 0 (implying True or False), it is called out as Boolean. The format
of each function is given as
ReturnType FunctionName(ParameterType parameter1, ParameterType parameter2, ...)
Optional parameters are given within square brackets.
AnyType eval(AnyType Expr)
Evaluates Expr as a string and then returns the result of evaluating the contents
of the string as a ClassAd expression. This is useful when referring to an
attribute such as slotX_State where X, the desired slot number is an expression,
such as SlotID+10. In such a case, if attribute SlotID is 5, the value of the
attribute slot15_State can be referenced using the expression eval(strcat("slot",
SlotID+10,"_State")). Function strcat() calls function string() on the second
parameter, which evaluates the expression, and then converts the integer result 15
to the string "15". The concatenated string returned by strcat() is "slot15_State",
and this string is then evaluated.
Note that referring to attributes of a job from within the string passed to eval()
in the Requirements or Rank expressions could cause inaccuracies in HTCondor's
automatic auto-clustering of jobs into equivalent groups for matchmaking purposes.
This is because HTCondor needs to determine which ClassAd attributes are
significant for matchmaking purposes, and indirect references from within the
string passed to eval() will not be counted.
String unparse(Attribute attr)
This function looks up the value of the provided attribute and returns the unparsed
version as a string. The attribute's value is not evaluated. If the attribute's
value is x + 3, then the function would return the string "x + 3". If the provided
attribute cannot be found, an empty string is returned.
This function returns ERROR if other than exactly 1 argument is given or the
argument is not an attribute reference.
String unresolved(Attribute attr)
This function returns the external attribute references and unresolved attribute
references of the expression that is the value of the provided attribute. If the
provided attribute cannot be found, then undefined is returned.
For example, in a typical job ClassAd if the Requirements expression has the value
OpSys == "LINUX" && TARGET.Arch == "ARM" && Cpus >= RequestCpus, then
unresolved(Requirements) will return "Arch,Cpus,OpSys" because those will not be
attributes of the job ClassAd.
Boolean unresolved(Attribute attr, String pattern)
This function returns True when at least one of the external or unresolved
attribute references of the expression that is the value of the provided attribute
matches the given Perl regular expression pattern. If none of the references match
the pattern, then False is returned. If the provided attribute cannot be found,
then undefined is returned.
For example, in a typical job ClassAd if the Requirements expression has the value
OpSys == "LINUX" && Arch == "ARM", then unresolved(Requirements, "^OpSys") will
return True, and unresolved(Requirements, "OpSys.+") will return False.
The intended use of this function is to make it easier to apply a submit transform
to a job only when the job does not already reference a certain attribute. For
instance
JOB_TRANSFORM_DefPlatform @=end
# Apply this transform only when the job requirements does not reference OpSysAndver or OpSysName
REQUIREMENTS ! unresolved(Requirements, "OpSys.+")
# Add a clause to the job requirements to match only CentOs7 machines
SET Requirements $(MY.Requirements) && OpSysAndVer == "CentOS7"
@end
AnyType ifThenElse(AnyType IfExpr,AnyType ThenExpr, AnyType ElseExpr)
A conditional expression is described by IfExpr. The following defines return
values, when IfExpr evaluates to
• True. Evaluate and return the value as given by ThenExpr.
• False. Evaluate and return the value as given by ElseExpr.
• UNDEFINED. Return the value UNDEFINED.
• ERROR. Return the value ERROR.
• 0.0. Evaluate, and return the value as given by ElseExpr.
• non-0.0 Real values. Evaluate, and return the value as given by ThenExpr.
Where IfExpr evaluates to give a value of type String, the function returns the
value ERROR. The implementation uses lazy evaluation, so expressions are only
evaluated as defined.
This function returns ERROR if other than exactly 3 arguments are given.
Boolean isUndefined(AnyType Expr)
Returns True, if Expr evaluates to UNDEFINED. Returns False in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isError(AnyType Expr)
Returns True, if Expr evaluates to ERROR. Returns False in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isString(AnyType Expr)
Returns True, if the evaluation of Expr gives a value of type String. Returns False
in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isInteger(AnyType Expr)
Returns True, if the evaluation of Expr gives a value of type Integer. Returns
False in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isReal(AnyType Expr)
Returns True, if the evaluation of Expr gives a value of type Real. Returns False
in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isList(AnyType Expr)
Returns True, if the evaluation of Expr gives a value of type List. Returns False
in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isClassAd(AnyType Expr)
Returns True, if the evaluation of Expr gives a value of type ClassAd. Returns
False in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isBoolean(AnyType Expr)
Returns True, if the evaluation of Expr gives the integer value 0 or 1. Returns
False in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isAbstime(AnyType Expr)
Returns True, if the evaluation of Expr returns an abstime type. Returns False in
all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean isReltime(AnyType Expr)
Returns True, if the evaluation of Expr returns an relative time type. Returns
False in all other cases.
This function returns ERROR if other than exactly 1 argument is given.
Boolean member(AnyType m, ListType l)
Returns error if m does not evalute to a scalar, or l does not evaluate to a list.
Otherwise the elements of l are evaluted in order, and if an element is equal to m
in the sense of == the result of the function is True. Otherwise the function
returns false.
Boolean anyCompare(string op, list l, AnyType t)
Returns error if op does not evalute to one of <, <=, ==, >, >=, !-, is or isnt.
Returns error if l isn't a list, or t isn't a scalar Otherwise the elements of l
are evaluted and compared to t using the corresponding operator defined by op. If
any of the members of l evaluate to true, the result is True. Otherwise the
function returns False.
Boolean allCompare(string op, list l, AnyType t)
Returns error if op does not evalute to one of <, <=, ==, >, >=, !-, is or isnt.
Returns error if l isn't a list, or t isn't a scalar Otherwise the elements of l
are evaluted and compared to t using the corresponding operator defined by op. If
all of the members of l evaluate to true, the result is True. Otherwise the
function returns False.
Boolean identicalMember(AnyType m, ListType l)
Returns error if m does not evalute to a scalar, or l does not evaluate to a list.
Otherwise the elements of l are evaluted in order, and if an element is equal to m
in the sense of =?= the result of the function is True. Otherwise the function
returns false.
Integer int(AnyType Expr)
Returns the integer value as defined by Expr. Where the type of the evaluated Expr
is Real, the value is truncated (round towards zero) to an integer. Where the type
of the evaluated Expr is String, the string is converted to an integer using a
C-like atoi() function. When this result is not an integer, ERROR is returned.
Where the evaluated Expr is ERROR or UNDEFINED, ERROR is returned.
This function returns ERROR if other than exactly 1 argument is given.
Real real(AnyType Expr)
Returns the real value as defined by Expr. Where the type of the evaluated Expr is
Integer, the return value is the converted integer. Where the type of the evaluated
Expr is String, the string is converted to a real value using a C-like atof()
function. When this result is not a real, ERROR is returned. Where the evaluated
Expr is ERROR or UNDEFINED, ERROR is returned.
This function returns ERROR if other than exactly 1 argument is given.
String string(AnyType Expr)
Returns the string that results from the evaluation of Expr. Converts a non-string
value to a string. Where the evaluated Expr is ERROR or UNDEFINED, ERROR is
returned.
This function returns ERROR if other than exactly 1 argument is given.
Bool bool(AnyType Expr)
Returns the boolean that results from the evaluation of Expr. Converts a
non-boolean value to a bool. A string expression that evaluates to the string
"true" yields true, and "false" returns
This function returns ERROR if other than exactly 1 argument is given.
AbsTime absTime(AnyType t [, int z])
Creates an AbsTime value corresponding to time t an time-zone offset z. If t is a
String, then z must be omitted, and t is parsed as a specification as follows.
The operand t is parsed as a specification of an instant in time (date and time).
This function accepts the canonical native representation of AbsTime values, but
minor variations in format are allowed. The default format is
yyyy-mm-ddThh:mm:sszzzzz where zzzzz is a time zone in the format +hh:mm or -hh:mm
If t and z are both omitted, the result is an AbsTime value representing the time
and place where the function call is evaluated. Otherwise, t is converted to a Real
by the function “real”, and treated as a number of seconds from the epoch, Midnight
January 1, 1970 UTC. If z is specified, it is treated as a number of seconds east
of Greenwich. Otherwise, the offset is calculated from t according to the local
rules for the place where the function is evaluated.
RelTime relTime(AnyType t)
If the operand t is a String, it is parsed as a specification of a time interval.
This function accepts the canonical native representation of RelTime values, but
minor variations in format are allowed.
Otherwise, t is converted to a Real by the function real, and treated as a number
of seconds. The default string format is [-]days+hh:mm:ss.fff, where leading
components and the fraction .fff are omitted if they are zero. In the default
syntax, days is a sequence of digits starting with a non-zero digit, hh, mm, and ss
are strings of exactly two digits (padded on the left with zeros if necessary) with
values less than 24, 60, and 60, respectively and fff is a string of exactly three
digits.
Integer floor(AnyType Expr)
Returns the integer that results from the evaluation of Expr, where the type of the
evaluated Expr is Integer. Where the type of the evaluated Expr is not Integer,
function real(Expr) is called. Its return value is then used to return the largest
magnitude integer that is not larger than the returned value. Where real(Expr)
returns ERROR or UNDEFINED, ERROR is returned.
This function returns ERROR if other than exactly 1 argument is given.
Integer ceiling(AnyType Expr)
Returns the integer that results from the evaluation of Expr, where the type of the
evaluated Expr is Integer. Where the type of the evaluated Expr is not Integer,
function real(Expr) is called. Its return value is then used to return the smallest
magnitude integer that is not less than the returned value. Where real(Expr)
returns ERROR or UNDEFINED, ERROR is returned.
This function returns ERROR if other than exactly 1 argument is given.
Integer pow(Integer base, Integer exponent) OR Real pow(Integer base, Integer exponent) OR
Real pow(Real base, Real exponent)
Calculates base raised to the power of exponent. If exponent is an integer value
greater than or equal to 0, and base is an integer, then an integer value is
returned. If exponent is an integer value less than 0, or if either base or
exponent is a real, then a real value is returned. An invocation with exponent=0 or
exponent=0.0, for any value of base, including 0 or 0.0, returns the value 1 or
1.0, type appropriate.
Integer quantize(AnyType a, Integer b) OR Real quantize(AnyType a, Real b) OR AnyType
quantize(AnyType a, AnyType list b)
quantize() computes the quotient of a/b, in order to further compute ``
ceiling(quotient) * b``. This computes and returns an integral multiple of b that
is at least as large as a. So, when b >= a, the return value will be b. The return
type is the same as that of b, where b is an Integer or Real.
When b is a list, quantize() returns the first value in the list that is greater
than or equal to a. When no value in the list is greater than or equal to a, this
computes and returns an integral multiple of the last member in the list that is at
least as large as a.
This function returns ERROR if a or b, or a member of the list that must be
considered is not an Integer or Real.
Here are examples:
8 = quantize(3, 8)
4 = quantize(3, 2)
0 = quantize(0, 4)
6.8 = quantize(1.5, 6.8)
7.2 = quantize(6.8, 1.2)
10.2 = quantize(10, 5.1)
4 = quantize(0, {4})
2 = quantize(2, {1, 2, "A"})
3.0 = quantize(3, {1, 2, 0.5})
3.0 = quantize(2.7, {1, 2, 0.5})
ERROR = quantize(3, {1, 2, "A"})
Integer round(AnyType Expr)
Returns the integer that results from the evaluation of Expr, where the type of the
evaluated Expr is Integer. Where the type of the evaluated Expr is not Integer,
function real(Expr) is called. Its return value is then used to return the integer
that results from a round-to-nearest rounding method. The nearest integer value to
the return value is returned, except in the case of the value at the exact midpoint
between two integer values. In this case, the even valued integer is returned.
Where real(Expr) returns ERROR or UNDEFINED, or the integer value does not fit into
32 bits, ERROR is returned.
This function returns ERROR if other than exactly 1 argument is given.
Integer random([ AnyType Expr ])
Where the optional argument Expr evaluates to type Integer or type Real (and called
x), the return value is the integer or real r randomly chosen from the interval 0
<= r < x. With no argument, the return value is chosen with random(1.0). Returns
ERROR in all other cases.
This function returns ERROR if greater than 1 argument is given.
Number sum([ List l ])
The elements of l are evaluated, producing a list l of values. Undefined values are
removed. If the resulting l is composed only of numbers, the result is the sum of
the values, as a Real if any value is Real, and as an Integer otherwise. If the
list is empty, the result is 0. If the list has only Undefined values, the result
is UNDEFINED. In other cases, the result is ERROR.
This function returns ERROR if greater than 1 argument is given.
Number avg([ List l ])
The elements of l are evaluated, producing a list l of values. Undefined values are
removed. If the resulting l is composed only of numbers, the result is the average
of the values, as a Real. If the list is empty, the result is 0. If the list has
only Undefined values, the result is UNDEFINED. In other cases, the result is
ERROR.
Number min([ List l ])
The elements of l are evaluated, producing a list l of values. Undefined values
are removed. If the resulting l is composed only of numbers, the result is the
minimum of the values, as a Real if any value is Real, and as an Integer otherwise.
If the list is empty, the result is UNDEFINED. In other cases, the result is ERROR.
Number max([ List l ])
The elements of l are evaluated, producing a list l of values. Undefined values
are removed. If the resulting l is composed only of numbers, the result is the
maximum of the values, as a Real if any value is Real, and as an Integer otherwise.
If the list is empty, the result is UNDEFINED. In other cases, the result is ERROR.
String strcat(AnyType Expr1 [ , AnyType Expr2 ...])
Returns the string which is the concatenation of all arguments, where all arguments
are converted to type String by function string(Expr). Returns ERROR if any
argument evaluates to UNDEFINED or ERROR.
String join(String sep, AnyType Expr1 [ , AnyType Expr2 ...]) OR String join(String sep,
List list OR String join(List list
Returns the string which is the concatenation of all arguments after the first one.
The first argument is the separator, and it is inserted between each of the other
arguments during concatenation. All arguments which are not undefined are
converted to type String by function string(Expr) before concatenation. Undefined
arguments are skipped. When there are exactly two arguments, If the second
argument is a List, all members of the list are converted to strings and then
joined using the separator. When there is only one argument, and the argument is a
List, all members of the list are converted to strings and then concatenated.
Returns ERROR if any argument evaluates to UNDEFINED or ERROR.
For example:
"a, b, c" = join(", ", "a", "b", "c")
"abc" = join(split("a b c"))
"a;b;c" = join(";", split("a b c"))
String substr(String s, Integer offset [ , Integer length ])
Returns the substring of s, from the position indicated by offset, with (optional)
length characters. The first character within s is at offset 0. If the optional
length argument is not present, the substring extends to the end of the string. If
offset is negative, the value (length - offset) is used for the offset. If length
is negative, an initial substring is computed, from the offset to the end of the
string. Then, the absolute value of length characters are deleted from the right
end of the initial substring. Further, where characters of this resulting substring
lie outside the original string, the part that lies within the original string is
returned. If the substring lies completely outside of the original string, the null
string is returned.
This function returns ERROR if greater than 3 or less than 2 arguments are given.
Integer strcmp(AnyType Expr1, AnyType Expr2)
Both arguments are converted to type String by function string(Expr). The return
value is an integer that will be
• less than 0, if Expr1 is lexicographically less than Expr2
• equal to 0, if Expr1 is lexicographically equal to Expr2
• greater than 0, if Expr1 is lexicographically greater than Expr2
Case is significant in the comparison. Where either argument evaluates to ERROR or
UNDEFINED, ERROR is returned.
This function returns ERROR if other than 2 arguments are given.
Integer stricmp(AnyType Expr1, AnyType Expr2)
This function is the same as strcmp, except that letter case is not significant.
Integer versioncmp(String left, String right)
This function version-compares two strings. It returns an integer
• less than zero if left is an earlier version than right
• zero if the strings are identical
• more than zero if left is a later version than right.
A version comparison is a lexicographic comparison unless the first difference
between the two strings occurs in a string of digits, in which case, sort by the
value of that number (assuming that more leading zeroes mean smaller numbers).
Thus 7.x is earlier than 7.y, 7.9 is earlier than 7.10, and the following sequence
is in order: 000, 00, 01, 010, 09, 0, 1, 9, 10.
Boolean versionGT(String left, String right) Boolean versionLT(String left, String right)
Boolean versionGE(String left, String right) Boolean versionLE(String left, String right)
Boolean versionEQ(String left, String right)
As versioncmp() (above), but for a specific comparison and returning a boolean. The
two letter codes stand for "Greater Than", "Less Than", "Greater than or Equal", "Less
than or Equal", and "EQual", respectively.
Boolean version_in_range(String version, String min, String max)
Equivalent to versionLE(min, version) && versionLE(version, max).
String toUpper(AnyType Expr)
The single argument is converted to type String by function string(Expr). The
return value is this string, with all lower case letters converted to upper case.
If the argument evaluates to ERROR or UNDEFINED, ERROR is returned.
This function returns ERROR if other than exactly 1 argument is given.
String toLower(AnyType Expr)
The single argument is converted to type String by function string(Expr). The
return value is this string, with all upper case letters converted to lower case.
If the argument evaluates to ERROR or UNDEFINED, ERROR is returned.
This function returns ERROR if other than exactly 1 argument is given.
Integer size(AnyType Expr)
If Expr evaluates to a string, return the number of characters in the string. If
Expr evaluate to a list, return the number of elements in the list. If Expr
evaluate to a classad, return the number of entries in the ad. Otherwise, ERROR is
returned.
List split(String s [ , String tokens ] )
Returns a list of the substrings of s that have been split up by using any of the
characters within string tokens. If tokens is not specified, then all white space
characters are used to delimit the string.
List splitUserName(String Name)
Returns a list of two strings. Where Name includes an @ character, the first string
in the list will be the substring that comes before the @ character, and the second
string in the list will be the substring that comes after. Thus, if Name is
"user@domain", then the returned list will be {"user", "domain"}. If there is no @
character in Name, then the first string in the list will be Name, and the second
string in the list will be the empty string. Thus, if Name is "username", then the
returned list will be {"username", ""}.
List splitSlotName(String Name)
Returns a list of two strings. Where Name includes an @ character, the first string
in the list will be the substring that comes before the @ character, and the second
string in the list will be the substring that comes after. Thus, if Name is
"slot1@machine", then the returned list will be {"slot1", "machine"}. If there is
no @ character in Name, then the first string in the list will be the empty string,
and the second string in the list will be Name, Thus, if Name is "machinename",
then the returned list will be {"", "machinename"}.
Integer time()
Returns the current coordinated universal time. This is the time, in seconds, since
midnight of January 1, 1970.
String formatTime([ Integer time ] [ , String format ])
Returns a formatted string that is a representation of time. The argument time is
interpreted as coordinated universal time in seconds, since midnight of January 1,
1970. If not specified, time will default to the current time.
The argument format is interpreted similarly to the format argument of the ANSI C
strftime function. It consists of arbitrary text plus placeholders for elements of
the time. These placeholders are percent signs (%) followed by a single letter. To
have a percent sign in the output, use a double percent sign (%%). If format is not
specified, it defaults to %c.
Because the implementation uses strftime() to implement this, and some versions
implement extra, non-ANSI C options, the exact options available to an
implementation may vary. An implementation is only required to implement the ANSI C
options, which are:
%a abbreviated weekday name
%A full weekday name
%b abbreviated month name
%B full month name
%c local date and time representation
%d day of the month (01-31)
%H hour in the 24-hour clock (0-23)
%I hour in the 12-hour clock (01-12)
%j day of the year (001-366)
%m month (01-12)
%M minute (00-59)
%p local equivalent of AM or PM
%S second (00-59)
%U week number of the year (Sunday as first day of week) (00-53)
%w weekday (0-6, Sunday is 0)
%W week number of the year (Monday as first day of week) (00-53)
%x local date representation
%X local time representation
%y year without century (00-99)
%Y year with century
%Z time zone name, if any
String interval(Integer seconds)
Uses seconds to return a string of the form days+hh:mm:ss. This represents an
interval of time. Leading values that are zero are omitted from the string. For
example, seconds of 67 becomes "1:07". A second example, seconds of 1472523 =
17*24*60*60 + 1*60*60 + 2*60 + 3, results in the string "17+1:02:03".
String evalInEachContext(Expression expr, List contexts)
This function evaluates its first argument as an expression in the context of each
Classad in the second argument and returns a list that is the result of each
evaluation. The first argument should be an expression. If the second argument
does not evaluate to a list of ClassAds, ERROR is returned.
For example:
{true, false} = evalInEachContext(Prio > 2, { [Prio=3;], [Prio=1;] })
{3, 1} = evalInEachContext(Prio, { [Prio=3;], [Prio=1;] })
ERROR = evalInEachContext(Prio > 2, { [Prio=3;], UNDEFINED })
ERROR = evalInEachContext(Prio > 2, UNDEFINED)
String countMatches(Expression expr, List contexts)
This function evaluates its first argument as an expression in the context of each
Classad in the second argument and returns a count of the results that evaluated to
True. The first argument should be an expression. The second argument should be a
list of ClassAds or a list of attribute references to classAds, or should evaluate
to a list of ClassAds. This function will always return a integer value when the
first argument is defined and the second argument is not ERROR.
For example:
1 = countMatches(Prio > 2, { [Prio=3;], [Prio=1;] })
1 = countMatches(Prio > 2, { [Prio=3;], UNDEFINED })
0 = countMatches(Prio > 2, UNDEFINED)
AnyType debug(AnyType expression)
This function evaluates its argument, and it returns the result. Thus, it is a
no-operation. However, a side-effect of the function is that information about the
evaluation is logged to the evaluating program's log file, at the D_FULLDEBUG debug
level. This is useful for determining why a given ClassAd expression is evaluating
the way it does. For example, if a condor_startd START expression is unexpectedly
evaluating to UNDEFINED, then wrapping the expression in this debug() function will
log information about each component of the expression to the log file, making it
easier to understand the expression.
String envV1ToV2(String old_env)
This function converts a set of environment variables from the old HTCondor syntax
to the new syntax. The single argument should evaluate to a string that represents
a set of environment variables using the old HTCondor syntax (usually stored in the
job ClassAd attribute Env). The result is the same set of environment variables
using the new HTCondor syntax (usually stored in the job ClassAd attribute
Environment). If the argument evaluates to UNDEFINED, then the result is also
UNDEFINED.
String mergeEnvironment(String env1 [ , String env2, ... ])
This function merges multiple sets of environment variables into a single set. If
multiple arguments include the same variable, the one that appears last in the
argument list is used. Each argument should evaluate to a string which represents a
set of environment variables using the new HTCondor syntax or UNDEFINED, which is
treated like an empty string. The result is a string that represents the merged set
of environment variables using the new HTCondor syntax (suitable for use as the
value of the job ClassAd attribute Environment).
For the following functions, a delimiter is represented by a string. Each character
within the delimiter string delimits individual strings within a list of strings that is
given by a single string. The default delimiter contains the comma and space characters. A
string within the list is ended (delimited) by one or more characters within the delimiter
string.
Integer stringListSize(String list [ , String delimiter ])
Returns the number of elements in the string list, as delimited by the optional
delimiter string. Returns ERROR if either argument is not a string.
This function returns ERROR if other than 1 or 2 arguments are given.
Integer stringListSum(String list [ , String delimiter ]) OR Real stringListSum(String
list [ , String delimiter ])
Sums and returns the sum of all items in the string list, as delimited by the
optional delimiter string. If all items in the list are integers, the return value
is also an integer. If any item in the list is a real value (noninteger), the
return value is a real. If any item does not represent an integer or real value,
the return value is ERROR.
Real stringListAvg(String list [ , String delimiter ])
Sums and returns the real-valued average of all items in the string list, as
delimited by the optional delimiter string. If any item does not represent an
integer or real value, the return value is ERROR. A list with 0 items (the empty
list) returns the value 0.0.
Integer stringListMin(String list [ , String delimiter ]) OR Real stringListMin(String
list [ , String delimiter ])
Finds and returns the minimum value from all items in the string list, as delimited
by the optional delimiter string. If all items in the list are integers, the return
value is also an integer. If any item in the list is a real value (noninteger),
the return value is a real. If any item does not represent an integer or real
value, the return value is ERROR. A list with 0 items (the empty list) returns the
value UNDEFINED.
Integer stringListMax(String list [ , String delimiter ]) OR Real stringListMax(String
list [ , String delimiter ])
Finds and returns the maximum value from all items in the string list, as delimited
by the optional delimiter string. If all items in the list are integers, the return
value is also an integer. If any item in the list is a real value (noninteger),
the return value is a real. If any item does not represent an integer or real
value, the return value is ERROR. A list with 0 items (the empty list) returns the
value UNDEFINED.
Boolean stringListMember(String x, String list [ , String delimiter ])
Returns TRUE if item x is in the string list, as delimited by the optional
delimiter string. Returns FALSE if item x is not in the string list. Comparison is
done with strcmp(). The return value is ERROR, if any of the arguments are not
strings.
Boolean stringListIMember(String x, String list [ , String delimiter ])
Same as stringListMember(), but comparison is done with stricmp(), so letter case
is not relevant.
Integer stringListsIntersect(String list1, String list2 [ , String delimiter ])
Returns TRUE if the lists contain any matching elements, and returns FALSE if the
lists do not contain any matching elements. Returns ERROR if either argument is
not a string or if an incorrect number of arguments are given.
Boolean stringListSubsetMatch(String list1, String list2 [ , String delimiter ])
Returns TRUE if all item in the string list1 are also in the string list2, as
delimited by the optional delimiter string. Returns FALSE if list1 has any items
that are not in list2. Both lists are treated as sets. Empty items and duplicate
items are ignored. The return value is TRUE if list1 is UNDEFINED or empty and
list2 is any string value. The return value is FALSE if list1 is any string vlaue
and list2 is UNDEFINED. The return value is UNDEFINED if both list1 and list2 are
UNDEFINED. The return value is ERROR, if any of the arguments are not either
strings or UNDEFINED
Boolean stringListISubsetMatch(String list1, String list2 [ , String delimiter ])
Same as stringListSubsetMatch(), but the sets are case-insensitive.
The following six functions utilize regular expressions as defined and supported by the
PCRE library. See http://www.pcre.org for complete documentation of regular expressions.
The options argument to these functions is a string of special characters that modify the
use of the regular expressions. Inclusion of characters other than these as options are
ignored.
I or i Ignore letter case.
M or m Modifies the interpretation of the caret (^) and dollar sign ($) characters. The
caret character matches the start of a string, as well as after each newline
character. The dollar sign character matches before a newline character.
S or s The period matches any character, including the newline character.
F or f When doing substitution, return the full target string with substitutions applied.
Normally, only the substitute text is returned.
G or g When doing substitution, apply the substitution for every matching portion of the
target string (that doesn't overlap a previous match).
Boolean regexp(String pattern, String target [ , String options ])
Uses the regular expression given by string pattern to scan through the string
target. Returns TRUE when target matches the regular expression given by pattern.
Returns FALSE otherwise. If any argument is not a string, or if pattern does not
describe a valid regular expression, returns ERROR.
Boolean regexpMember(String pattern, List targetStrings [ , String options ])
Uses the description of a regular expression given by string pattern to scan
through a List of string n targetStrings. Returns TRUE when target matches a
regular expression given by pattern. If no strings match, and at least one item in
targetString evaluated to undefined, returns undefined. If any item in
targetString before a match evaluated to neither a string nor undefined, returns
ERROR.
String regexps
(String pattern, String target, String substitute [ , String options ]) Uses the
regular expression given by string pattern to scan through the string target. When
target matches the regular expression given by pattern, the string substitute is
returned, with backslash expansion performed. If any argument is not a string,
returns ERROR.
String replace
(String pattern, String target, String substitute [ , String options ]) Uses the
regular expression given by string pattern to scan through the string target.
Returns a modified version of target, where the first substring that matches
pattern is replaced by the string substitute, with backslash expansion performed.
Equivalent to regexps() with the f option. If any argument is not a string, returns
ERROR.
String replaceall
(String pattern, String target, String substitute [ , String options ]) Uses the
regular expression given by string pattern to scan through the string target.
Returns a modified version of target, where every substring that matches pattern is
replaced by the string substitute, with backslash expansion performed. Equivalent
to regexps() with the fg options. If any argument is not a string, returns ERROR.
Boolean stringList_regexpMember
(String pattern, String list [ , String delimiter ] [ , String options ]) Uses the
description of a regular expression given by string pattern to scan through the
list of strings in list. Returns TRUE when one of the strings in list is a regular
expression as described by pattern. The optional delimiter describes how the list
is delimited, and string options modifies how the match is performed. Returns FALSE
if pattern does not match any entries in list. The return value is ERROR, if any of
the arguments are not strings, or if pattern is not a valid regular expression.
String userHome(String userName [ , String default ])
Returns the home directory of the given user as configured on the current system
(determined using the getpwdnam() call). (Returns default if the default argument
is passed and the home directory of the user is not defined.)
List userMap(String mapSetName, String userName)
Map an input string using the given mapping set. Returns a string containing the
list of groups to which the user belongs separated by commas or undefined if the
user was not found in the map file.
String userMap(String mapSetName, String userName, String preferredGroup)
Map an input string using the given mapping set. Returns a string, which is the
preferred group if the user is in that group; otherwise it is the first group to
which the user belongs, or undefined if the user belongs to no groups.
String userMap(String mapSetName, String userName, String preferredGroup, String
defaultGroup)
Map an input string using the given mapping set. Returns a string, which is the
preferred group if the user is in that group; the first group to which the user
belongs, if any; and the default group if the user belongs to no groups.
The maps for the userMap() function are defined by the following configuration
macros: <SUBSYS>_CLASSAD_USER_MAP_NAMES, CLASSAD_USER_MAPFILE_<name> and
CLASSAD_USER_MAPDATA_<name> (see the
admin-manual/configuration-macros:htcondor-wide configuration file entries
section).
CLASSAD EVALUATION SEMANTICS
The ClassAd mechanism's primary purpose is for matching entities that supply constraints
on candidate matches. The mechanism is therefore defined to carry out expression
evaluations in the context of two ClassAds that are testing each other for a potential
match. For example, the condor_negotiator evaluates the Requirements expressions of
machine and job ClassAds to test if they can be matched. The semantics of evaluating such
constraints is defined below.
Evaluating Literals
Literals are self-evaluating, Thus, integer, string, real, undefined and error values
evaluate to themselves.
Attribute References
Since the expression evaluation is being carried out in the context of two ClassAds, there
is a potential for name space ambiguities. The following rules define the semantics of
attribute references made by ClassAd A that is being evaluated in a context with another
ClassAd B:
1. If the reference is prefixed by a scope resolution prefix,
• If the prefix is MY., the attribute is looked up in ClassAd A. If the named
attribute does not exist in A, the value of the reference is UNDEFINED. Otherwise,
the value of the reference is the value of the expression bound to the attribute
name.
• Similarly, if the prefix is TARGET., the attribute is looked up in ClassAd B. If the
named attribute does not exist in B, the value of the reference is UNDEFINED.
Otherwise, the value of the reference is the value of the expression bound to the
attribute name.
2. If the reference is not prefixed by a scope resolution prefix,
• If the attribute is defined in A, the value of the reference is the value of the
expression bound to the attribute name in A.
• Otherwise, if the attribute is defined in B, the value of the reference is the value
of the expression bound to the attribute name in B.
• Otherwise, if the attribute is defined in the ClassAd environment, the value from the
environment is returned. This is a special environment, to be distinguished from the
Unix environment. Currently, the only attribute of the environment is CurrentTime,
which evaluates to the integer value returned by the system call time(2).
• Otherwise, the value of the reference is UNDEFINED.
3. Finally, if the reference refers to an expression that is itself in the process of
being evaluated, there is a circular dependency in the evaluation. The value of the
reference is ERROR.
ClassAd Operators
All operators in the ClassAd language are total, and thus have well defined behavior
regardless of the supplied operands. Furthermore, most operators are strict with respect
to ERROR and UNDEFINED, and thus evaluate to ERROR or UNDEFINED if either of their
operands have these exceptional values.
• Arithmetic operators:
1. The operators \*, /, + and - operate arithmetically only on integers and reals.
2. Arithmetic is carried out in the same type as both operands, and type promotions from
integers to reals are performed if one operand is an integer and the other real.
3. The operators are strict with respect to both UNDEFINED and ERROR.
4. If either operand is not a numerical type, the value of the operation is ERROR.
• Comparison operators:
1. The comparison operators ==, !=, <=, <, >= and > operate on integers, reals and
strings.
2. String comparisons are case insensitive for most operators. The only exceptions are
the operators =?= and =!=, which do case sensitive comparisons assuming both sides
are strings.
3. Comparisons are carried out in the same type as both operands, and type promotions
from integers to reals are performed if one operand is a real, and the other an
integer. Strings may not be converted to any other type, so comparing a string and an
integer or a string and a real results in ERROR.
4. The operators ==, !=, <=, <, >=, and > are strict with respect to both UNDEFINED and
ERROR.
5. In addition, the operators =?=, is, =!=, and isnt behave similar to == and !=, but
are not strict. Semantically, the =?= and is test if their operands are "identical,"
i.e., have the same type and the same value. For example, 10 == UNDEFINED and
UNDEFINED == UNDEFINED both evaluate to UNDEFINED, but 10 =?= UNDEFINED and UNDEFINED
is UNDEFINED evaluate to FALSE and TRUE respectively. The =!= and isnt operators test
for the "is not identical to" condition.
=?= and is have the same behavior as each other. And isnt and =!= behave the same as
each other. The ClassAd unparser will always use =?= in preference to is and =!= in
preference to isnt when printing out ClassAds.
• Logical operators:
1. The logical operators && and || operate on integers and reals. The zero value of
these types are considered FALSE and non-zero values TRUE.
2. The operators are not strict, and exploit the "don't care" properties of the
operators to squash UNDEFINED and ERROR values when possible. For example, UNDEFINED
&& FALSE evaluates to FALSE, but UNDEFINED || FALSE evaluates to UNDEFINED.
3. Any string operand is equivalent to an ERROR operand for a logical operator. In other
words, TRUE && "foobar" evaluates to ERROR.
• The Ternary operator:
1. The Ternary operator (expr1 ? expr2 : expr3) operate with expressions. If all three
expressions are given, the operation is strict.
2. However, if the middle expression is missing, eg. expr1 ?: expr3, then, when expr1 is
defined, that defined value is returned. Otherwise, when expr1 evaluated to
UNDEFINED, the value of expr3 is evaluated and returned. This can be a convenient
shortcut for writing what would otherwise be a much longer classad expression.
Expression Examples
The =?= operator is similar to the == operator. It checks if the left hand side operand is
identical in both type and value to the the right hand side operand, returning TRUE when
they are identical.
CAUTION:
For strings, the comparison is case-insensitive with the == operator and case-sensitive
with the =?= operator. A key point in understanding is that the =?= operator only
produces evaluation results of TRUE and FALSE, where the == operator may produce
evaluation results TRUE, FALSE, UNDEFINED, or ERROR.
Table 4.1 presents examples that define the outcome of the == operator. Table 4.2
presents examples that define the outcome of the =?= operator.
┌─────────────────────────┬──────────────────┐
│expression │ evaluated result │
├─────────────────────────┼──────────────────┤
│(10 == 10) │ TRUE │
├─────────────────────────┼──────────────────┤
│(10 == 5) │ FALSE │
├─────────────────────────┼──────────────────┤
│(10 == "ABC") │ ERROR │
├─────────────────────────┼──────────────────┤
│"ABC" == "abc" │ TRUE │
├─────────────────────────┼──────────────────┤
│(10 == UNDEFINED) │ UNDEFINED │
├─────────────────────────┼──────────────────┤
│(UNDEFINED == UNDEFINED) │ UNDEFINED │
└─────────────────────────┴──────────────────┘
Table 4.1: Evaluation examples for the == operator
┌──────────────────────────┬──────────────────┐
│expression │ evaluated result │
├──────────────────────────┼──────────────────┤
│(10 =?= 10) │ TRUE │
├──────────────────────────┼──────────────────┤
│(10 =?= 5) │ FALSE │
├──────────────────────────┼──────────────────┤
│(10 =?= "ABC") │ FALSE │
├──────────────────────────┼──────────────────┤
│"ABC" =?= "abc" │ FALSE │
├──────────────────────────┼──────────────────┤
│(10 =?= UNDEFINED) │ FALSE │
├──────────────────────────┼──────────────────┤
│(UNDEFINED =?= UNDEFINED) │ TRUE │
└──────────────────────────┴──────────────────┘
Table 4.2: Evaluation examples for the =?= operator
The =!= operator is similar to the != operator. It checks if the left hand side operand is
not identical in both type and value to the the right hand side operand, returning FALSE
when they are identical.
CAUTION:
For strings, the comparison is case-insensitive with the != operator and case-sensitive
with the =!= operator. A key point in understanding is that the =!= operator only
produces evaluation results of TRUE and FALSE, where the != operator may produce
evaluation results TRUE, FALSE, UNDEFINED, or ERROR.
Table 4.3 presents examples that define the outcome of the != operator. Table 4.4
presents examples that define the outcome of the =!= operator.
┌─────────────────────────┬──────────────────┐
│expression │ evaluated result │
├─────────────────────────┼──────────────────┤
│(10 != 10) │ FALSE │
├─────────────────────────┼──────────────────┤
│(10 != 5) │ TRUE │
├─────────────────────────┼──────────────────┤
│(10 != "ABC") │ ERROR │
├─────────────────────────┼──────────────────┤
│"ABC" != "abc" │ FALSE │
├─────────────────────────┼──────────────────┤
│(10 != UNDEFINED) │ UNDEFINED │
├─────────────────────────┼──────────────────┤
│(UNDEFINED != UNDEFINED) │ UNDEFINED │
└─────────────────────────┴──────────────────┘
Table 4.3: Evaluation examples for the != operator
┌──────────────────────────┬──────────────────┐
│expression │ evaluated result │
├──────────────────────────┼──────────────────┤
│(10 =!= 10) │ FALSE │
├──────────────────────────┼──────────────────┤
│(10 =!= 5) │ TRUE │
├──────────────────────────┼──────────────────┤
│(10 =!= "ABC") │ TRUE │
├──────────────────────────┼──────────────────┤
│"ABC" =!= "abc" │ TRUE │
├──────────────────────────┼──────────────────┤
│(10 =!= UNDEFINED) │ TRUE │
├──────────────────────────┼──────────────────┤
│(UNDEFINED =!= UNDEFINED) │ FALSE │
└──────────────────────────┴──────────────────┘
Table 4.4: Evaluation examples for the =!= operator
OLD CLASSADS IN THE HTCONDOR SYSTEM
The simplicity and flexibility of ClassAds is heavily exploited in the HTCondor system.
ClassAds are not only used to represent machines and jobs in the HTCondor pool, but also
other entities that exist in the pool such as submitters of jobs and master daemons.
Since arbitrary expressions may be supplied and evaluated over these ClassAds, users have
a uniform and powerful mechanism to specify constraints over these ClassAds. These
constraints can take the form of Requirements expressions in resource and job ClassAds, or
queries over other ClassAds.
Constraints and Preferences
The requirements and rank expressions within the submit description file are the mechanism
by which users specify the constraints and preferences of jobs. For machines, the
configuration determines both constraints and preferences of the machines.
For both machine and job, the rank expression specifies the desirability of the match
(where higher numbers mean better matches). For example, a job ClassAd may contain the
following expressions:
Requirements = (Arch == "INTEL") && (OpSys == "LINUX")
Rank = TARGET.Memory + TARGET.Mips
In this case, the job requires a 32-bit Intel processor running a Linux operating system.
Among all such computers, the customer prefers those with large physical memories and high
MIPS ratings. Since the Rank is a user-specified metric, any expression may be used to
specify the perceived desirability of the match. The condor_negotiator daemon runs
algorithms to deliver the best resource (as defined by the rank expression), while
satisfying other required criteria.
Similarly, the machine may place constraints and preferences on the jobs that it will run
by setting the machine's configuration. For example,
Friend = Owner == "tannenba" || Owner == "wright"
ResearchGroup = Owner == "jbasney" || Owner == "raman"
Trusted = Owner != "rival" && Owner != "riffraff"
START = Trusted && ( ResearchGroup || LoadAvg < 0.3 && KeyboardIdle > 15*60 )
RANK = Friend + ResearchGroup*10
The above policy states that the computer will never run jobs owned by users rival and
riffraff, while the computer will always run a job submitted by members of the research
group. Furthermore, jobs submitted by friends are preferred to other foreign jobs, and
jobs submitted by the research group are preferred to jobs submitted by friends.
Note: Because of the dynamic nature of ClassAd expressions, there is no a priori notion of
an integer-valued expression, a real-valued expression, etc. However, it is intuitive to
think of the Requirements and Rank expressions as integer-valued and real-valued
expressions, respectively. If the actual type of the expression is not of the expected
type, the value is assumed to be zero.
Querying with ClassAd Expressions
The flexibility of this system may also be used when querying ClassAds through the
condor_status and condor_q tools which allow users to supply ClassAd constraint
expressions from the command line.
Needed syntax is different on Unix and Windows platforms, due to the interpretation of
characters in forming command-line arguments. The expression must be a single command-line
argument, and the resulting examples differ for the platforms. For Unix shells, single
quote marks are used to delimit a single argument. For a Windows command window, double
quote marks are used to delimit a single argument. Within the argument, Unix escapes the
double quote mark by prepending a backslash to the double quote mark. Windows escapes the
double quote mark by prepending another double quote mark. There may not be spaces in
between.
Here are several examples. To find all computers which have had their keyboards idle for
more than 60 minutes and have more than 4000 MB of memory, the desired ClassAd expression
is
KeyboardIdle > 60*60 && Memory > 4000
On a Unix platform, the command appears as
$ condor_status -const 'KeyboardIdle > 60*60 && Memory > 4000'
Name OpSys Arch State Activity LoadAv Mem ActvtyTime
100
slot1@altair.cs.wi LINUX X86_64 Owner Idle 0.000 8018 13+00:31:46
slot2@altair.cs.wi LINUX X86_64 Owner Idle 0.000 8018 13+00:31:47
...
...
slot1@athena.stat. LINUX X86_64 Unclaimed Idle 0.000 7946 0+00:25:04
slot2@athena.stat. LINUX X86_64 Unclaimed Idle 0.000 7946 0+00:25:05
...
...
The Windows equivalent command is
> condor_status -const "KeyboardIdle > 60*60 && Memory > 4000"
Here is an example for a Unix platform that utilizes a regular expression ClassAd function
to list specific information. A file contains ClassAd information. condor_advertise is
used to inject this information, and condor_status constrains the search with an
expression that contains a ClassAd function.
$ cat ad
MyType = "Generic"
FauxType = "DBMS"
Name = "random-test"
Machine = "f05.cs.wisc.edu"
MyAddress = "<128.105.149.105:34000>"
DaemonStartTime = 1153192799
UpdateSequenceNumber = 1
$ condor_advertise UPDATE_AD_GENERIC ad
$ condor_status -any -constraint 'FauxType=="DBMS" && regexp("random.*", Name, "i")'
MyType TargetType Name
Generic None random-test
The ClassAd expression describing a machine that advertises a Windows operating system:
OpSys == "WINDOWS"
Here are three equivalent ways on a Unix platform to list all machines advertising a
Windows operating system. Spaces appear in these examples to show where they are
permitted.
$ condor_status -constraint ' OpSys == "WINDOWS" '
$ condor_status -constraint OpSys==\"WINDOWS\"
$ condor_status -constraint "OpSys==\"WINDOWS\""
The equivalent command on a Windows platform to list all machines advertising a Windows
operating system must delimit the single argument with double quote marks, and then escape
the needed double quote marks that identify the string within the expression. Spaces
appear in this example where they are permitted.
> condor_status -constraint " OpSys == ""WINDOWS"" "
EXTENDING CLASSADS WITH USER-WRITTEN FUNCTIONS
The ClassAd language provides a rich set of functions. It is possible to add new functions
to the ClassAd language without recompiling the HTCondor system or the ClassAd library.
This requires implementing the new function in the C++ programming language, compiling the
code into a shared library, and telling HTCondor where in the file system the shared
library lives.
While the details of the ClassAd implementation are beyond the scope of this document, the
ClassAd source distribution ships with an example source file that extends ClassAds by
adding two new functions, named todays_date() and double(). This can be used as a model
for users to implement their own functions. To deploy this example extension, follow the
following steps on Linux:
• Download the ClassAd source distribution from http://www.cs.wisc.edu/condor/classad.
• Unpack the tarball.
• Inspect the source file shared.cpp. This one file contains the whole extension.
• Build shared.cpp into a shared library. On Linux, the command line to do so is
$ g++ -DWANT_CLASSAD_NAMESPACE -I. -shared -o shared.so \
-Wl,-soname,shared.so -o shared.so -fPIC shared.cpp
• Copy the file shared.so to a location that all of the HTCondor tools and daemons can
read.
$ cp shared.so `condor_config_val LIBEXEC`
• Tell HTCondor to load the shared library into all tools and daemons, by setting the
CLASSAD_USER_LIBS configuration variable to the full name of the shared library. In this
case,
CLASSAD_USER_LIBS = $(LIBEXEC)/shared.so
• Restart HTCondor.
• Test the new functions by running
$ condor_status -format "%s\n" todays_date()
AUTHOR
HTCondor Team
COPYRIGHT
1990-2024, Center for High Throughput Computing, Computer Sciences Department, University
of Wisconsin-Madison, Madison, WI, US. Licensed under the Apache License, Version 2.0.
Apr 14, 2024 CLASSADS(1)