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NAME
find - find files
SYNOPSIS
find [-H | -L] path ... [operand_expression ...]
DESCRIPTION
The find utility shall recursively descend the directory hierarchy from each file specified by path,
evaluating a Boolean expression composed of the primaries described in the OPERANDS section for each file
encountered.
The find utility shall be able to descend to arbitrary depths in a file hierarchy and shall not fail due
to path length limitations (unless a path operand specified by the application exceeds {PATH_MAX}
requirements).
The find utility shall detect infinite loops; that is, entering a previously visited directory that is an
ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic
message to standard error and shall either recover its position in the hierarchy or terminate.
OPTIONS
The find utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2,
Utility Syntax Guidelines.
The following options shall be supported by the implementation:
-H Cause the file information and file type evaluated for each symbolic link encountered on the
command line to be those of the file referenced by the link, and not the link itself. If the
referenced file does not exist, the file information and type shall be for the link itself. File
information for all symbolic links not on the command line shall be that of the link itself.
-L Cause the file information and file type evaluated for each symbolic link to be those of the file
referenced by the link, and not the link itself.
Specifying more than one of the mutually-exclusive options -H and -L shall not be considered an error.
The last option specified shall determine the behavior of the utility.
OPERANDS
The following operands shall be supported:
The path operand is a pathname of a starting point in the directory hierarchy.
The first argument that starts with a '-' , or is a '!' or a '(' , and all subsequent arguments shall be
interpreted as an expression made up of the following primaries and operators. In the descriptions,
wherever n is used as a primary argument, it shall be interpreted as a decimal integer optionally
preceded by a plus ( '+' ) or minus ( '-' ) sign, as follows:
+n More than n.
n Exactly n.
-n Less than n.
The following primaries shall be supported:
-name pattern
The primary shall evaluate as true if the basename of the filename being examined matches pattern
using the pattern matching notation described in Pattern Matching Notation .
-nouser
The primary shall evaluate as true if the file belongs to a user ID for which the getpwuid()
function defined in the System Interfaces volume of IEEE Std 1003.1-2001 (or equivalent) returns
NULL.
-nogroup
The primary shall evaluate as true if the file belongs to a group ID for which the getgrgid()
function defined in the System Interfaces volume of IEEE Std 1003.1-2001 (or equivalent) returns
NULL.
-xdev The primary shall always evaluate as true; it shall cause find not to continue descending past
directories that have a different device ID ( st_dev, see the stat() function defined in the
System Interfaces volume of IEEE Std 1003.1-2001). If any -xdev primary is specified, it shall
apply to the entire expression even if the -xdev primary would not normally be evaluated.
-prune The primary shall always evaluate as true; it shall cause find not to descend the current pathname
if it is a directory. If the -depth primary is specified, the -prune primary shall have no
effect.
-perm [-]mode
The mode argument is used to represent file mode bits. It shall be identical in format to the
symbolic_mode operand described in chmod() , and shall be interpreted as follows. To start, a
template shall be assumed with all file mode bits cleared. An op symbol of '+' shall set the
appropriate mode bits in the template; '-' shall clear the appropriate bits; '=' shall set the
appropriate mode bits, without regard to the contents of process' file mode creation mask. The op
symbol of '-' cannot be the first character of mode; this avoids ambiguity with the optional
leading hyphen. Since the initial mode is all bits off, there are not any symbolic modes that need
to use '-' as the first character.
If the hyphen is omitted, the primary shall evaluate as true when the file permission bits exactly match
the value of the resulting template.
Otherwise, if mode is prefixed by a hyphen, the primary shall evaluate as true if at least all the bits
in the resulting template are set in the file permission bits.
-perm [-]onum
If the hyphen is omitted, the primary shall evaluate as true when the file permission bits exactly
match the value of the octal number onum and only the bits corresponding to the octal mask 07777
shall be compared. (See the description of the octal mode in chmod() .) Otherwise, if onum is
prefixed by a hyphen, the primary shall evaluate as true if at least all of the bits specified in
onum that are also set in the octal mask 07777 are set.
-type c
The primary shall evaluate as true if the type of the file is c, where c is 'b' , 'c' , 'd' , 'l'
, 'p' , 'f' , or 's' for block special file, character special file, directory, symbolic link,
FIFO, regular file, or socket, respectively.
-links n
The primary shall evaluate as true if the file has n links.
-user uname
The primary shall evaluate as true if the file belongs to the user uname. If uname is a decimal
integer and the getpwnam() (or equivalent) function does not return a valid user name, uname shall
be interpreted as a user ID.
-group gname
The primary shall evaluate as true if the file belongs to the group gname. If gname is a decimal
integer and the getgrnam() (or equivalent) function does not return a valid group name, gname
shall be interpreted as a group ID.
-size n[c]
The primary shall evaluate as true if the file size in bytes, divided by 512 and rounded up to the
next integer, is n. If n is followed by the character 'c' , the size shall be in bytes.
-atime n
The primary shall evaluate as true if the file access time subtracted from the initialization
time, divided by 86400 (with any remainder discarded), is n.
-ctime n
The primary shall evaluate as true if the time of last change of file status information
subtracted from the initialization time, divided by 86400 (with any remainder discarded), is n.
-mtime n
The primary shall evaluate as true if the file modification time subtracted from the
initialization time, divided by 86400 (with any remainder discarded), is n.
-exec utility_name [argument ...] ;
-exec utility_name [argument ...]
{} +
The end of the primary expression shall be punctuated by a semicolon or by a plus sign. Only a
plus sign that follows an argument containing the two characters "{}" shall punctuate the end of
the primary expression. Other uses of the plus sign shall not be treated as special.
If the primary expression is punctuated by a semicolon, the utility utility_name shall be invoked once
for each pathname and the primary shall evaluate as true if the utility returns a zero value as exit
status. A utility_name or argument containing only the two characters "{}" shall be replaced by the
current pathname.
If the primary expression is punctuated by a plus sign, the primary shall always evaluate as true, and
the pathnames for which the primary is evaluated shall be aggregated into sets. The utility utility_name
shall be invoked once for each set of aggregated pathnames. Each invocation shall begin after the last
pathname in the set is aggregated, and shall be completed before the find utility exits and before the
first pathname in the next set (if any) is aggregated for this primary, but it is otherwise unspecified
whether the invocation occurs before, during, or after the evaluations of other primaries. If any
invocation returns a non-zero value as exit status, the find utility shall return a non-zero exit status.
An argument containing only the two characters "{}" shall be replaced by the set of aggregated pathnames,
with each pathname passed as a separate argument to the invoked utility in the same order that it was
aggregated. The size of any set of two or more pathnames shall be limited such that execution of the
utility does not cause the system's {ARG_MAX} limit to be exceeded. If more than one argument containing
only the two characters "{}" is present, the behavior is unspecified.
If a utility_name or argument string contains the two characters "{}" , but not just the two characters
"{}" , it is implementation-defined whether find replaces those two characters or uses the string without
change. The current directory for the invocation of utility_name shall be the same as the current
directory when the find utility was started. If the utility_name names any of the special built-in
utilities (see Special Built-In Utilities ), the results are undefined.
-ok utility_name [argument ...] ;
The -ok primary shall be equivalent to -exec, except that the use of a plus sign to punctuate the
end of the primary expression need not be supported, and find shall request affirmation of the
invocation of utility_name using the current file as an argument by writing to standard error as
described in the STDERR section. If the response on standard input is affirmative, the utility
shall be invoked. Otherwise, the command shall not be invoked and the value of the -ok operand
shall be false.
-print The primary shall always evaluate as true; it shall cause the current pathname to be written to
standard output.
-newer file
The primary shall evaluate as true if the modification time of the current file is more recent
than the modification time of the file named by the pathname file.
-depth The primary shall always evaluate as true; it shall cause descent of the directory hierarchy to be
done so that all entries in a directory are acted on before the directory itself. If a -depth
primary is not specified, all entries in a directory shall be acted on after the directory itself.
If any -depth primary is specified, it shall apply to the entire expression even if the -depth
primary would not normally be evaluated.
The primaries can be combined using the following operators (in order of decreasing precedence):
( expression )
True if expression is true.
! expression
Negation of a primary; the unary NOT operator.
expression [-a] expression
Conjunction of primaries; the AND operator is implied by the juxtaposition of two primaries or
made explicit by the optional -a operator. The second expression shall not be evaluated if the
first expression is false.
expression -o expression
Alternation of primaries; the OR operator. The second expression shall not be evaluated if the
first expression is true.
If no expression is present, -print shall be used as the expression. Otherwise, if the given expression
does not contain any of the primaries -exec, -ok, or -print, the given expression shall be effectively
replaced by:
( given_expression ) -print
The -user, -group, and -newer primaries each shall evaluate their respective arguments only once.
STDIN
If the -ok primary is used, the response shall be read from the standard input. An entire line shall be
read as the response. Otherwise, the standard input shall not be used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of find:
LANG Provide a default value for the internationalization variables that are unset or null. (See the
Base Definitions volume of IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for
the precedence of internationalization variables used to determine the values of locale
categories.)
LC_ALL If set to a non-empty string value, override the values of all the other internationalization
variables.
LC_COLLATE
Determine the locale for the behavior of ranges, equivalence classes, and multi-character
collating elements used in the pattern matching notation for the -n option and in the extended
regular expression defined for the yesexpr locale keyword in the LC_MESSAGES category.
LC_CTYPE
This variable determines the locale for the interpretation of sequences of bytes of text data as
characters (for example, single-byte as opposed to multi-byte characters in arguments), the
behavior of character classes within the pattern matching notation used for the -n option, and the
behavior of character classes within regular expressions used in the extended regular expression
defined for the yesexpr locale keyword in the LC_MESSAGES category.
LC_MESSAGES
Determine the locale for the processing of affirmative responses that should be used to affect the
format and contents of diagnostic messages written to standard error.
NLSPATH
Determine the location of message catalogs for the processing of LC_MESSAGES .
PATH Determine the location of the utility_name for the -exec and -ok primaries, as described in the
Base Definitions volume of IEEE Std 1003.1-2001, Chapter 8, Environment Variables.
ASYNCHRONOUS EVENTS
Default.
STDOUT
The -print primary shall cause the current pathnames to be written to standard output. The format shall
be:
"%s\n", <path>
STDERR
The -ok primary shall write a prompt to standard error containing at least the utility_name to be invoked
and the current pathname. In the POSIX locale, the last non- <blank> in the prompt shall be '?' . The
exact format used is unspecified.
Otherwise, the standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 All path operands were traversed successfully.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
When used in operands, pattern matching notation, semicolons, opening parentheses, and closing
parentheses are special to the shell and must be quoted (see Quoting ).
The bit that is traditionally used for sticky (historically 01000) is specified in the -perm primary
using the octal number argument form. Since this bit is not defined by this volume of
IEEE Std 1003.1-2001, applications must not assume that it actually refers to the traditional sticky bit.
EXAMPLES
1. The following commands are equivalent:
find .
find . -print
They both write out the entire directory hierarchy from the current directory.
2. The following command:
find / \( -name tmp -o -name '*.xx' \) -atime +7 -exec rm {} \;
removes all files named tmp or ending in .xx that have not been accessed for seven or more 24-hour
periods.
3. The following command:
find . -perm -o+w,+s
prints ( -print is assumed) the names of all files in or below the current directory, with all of the
file permission bits S_ISUID, S_ISGID, and S_IWOTH set.
4. The following command:
find . -name SCCS -prune -o -print
recursively prints pathnames of all files in the current directory and below, but skips directories named
SCCS and files in them.
5. The following command:
find . -print -name SCCS -prune
behaves as in the previous example, but prints the names of the SCCS directories.
6. The following command is roughly equivalent to the -nt extension to test:
if [ -n "$(find file1 -prune -newer file2)" ]; then
printf %s\\n "file1 is newer than file2"
fi
7. The descriptions of -atime, -ctime, and -mtime use the terminology n "86400 second periods (days)".
For example, a file accessed at 23:59 is selected by:
find . -atime -1 -print
at 00:01 the next day (less than 24 hours later, not more than one day ago); the midnight boundary
between days has no effect on the 24-hour calculation.
RATIONALE
The -a operator was retained as an optional operator for compatibility with historical shell scripts,
even though it is redundant with expression concatenation.
The descriptions of the '-' modifier on the mode and onum arguments to the -perm primary agree with
historical practice on BSD and System V implementations. System V and BSD documentation both describe it
in terms of checking additional bits; in fact, it uses the same bits, but checks for having at least all
of the matching bits set instead of having exactly the matching bits set.
The exact format of the interactive prompts is unspecified. Only the general nature of the contents of
prompts are specified because:
* Implementations may desire more descriptive prompts than those used on historical implementations.
* Since the historical prompt strings do not terminate with <newline>s, there is no portable way for
another program to interact with the prompts of this utility via pipes.
Therefore, an application using this prompting option relies on the system to provide the most suitable
dialog directly with the user, based on the general guidelines specified.
The -name file operand was changed to use the shell pattern matching notation so that find is consistent
with other utilities using pattern matching.
The -size operand refers to the size of a file, rather than the number of blocks it may occupy in the
file system. The intent is that the st_size field defined in the System Interfaces volume of
IEEE Std 1003.1-2001 should be used, not the st_blocks found in historical implementations. There are at
least two reasons for this:
1. In both System V and BSD, find only uses st_size in size calculations for the operands specified by
this volume of IEEE Std 1003.1-2001. (BSD uses st_blocks only when processing the -ls primary.)
2. Users usually think of file size in terms of bytes, which is also the unit used by the ls utility for
the output from the -l option. (In both System V and BSD, ls uses st_size for the -l option size
field and uses st_blocks for the ls -s calculations. This volume of IEEE Std 1003.1-2001 does not
specify ls -s.)
The descriptions of -atime, -ctime, and -mtime were changed from the SVID description of n "days'' to
"24-hour periods". The description is also different in terms of the exact timeframe for the n case
(versus the +n or -n), but it matches all known historical implementations. It refers to one 86400
second period in the past, not any time from the beginning of that period to the current time. For
example, -atime 3 is true if the file was accessed any time in the period from 72 hours to 48 hours ago.
Historical implementations do not modify "{}" when it appears as a substring of an -exec or -ok
utility_name or argument string. There have been numerous user requests for this extension, so this
volume of IEEE Std 1003.1-2001 allows the desired behavior. At least one recent implementation does
support this feature, but encountered several problems in managing memory allocation and dealing with
multiple occurrences of "{}" in a string while it was being developed, so it is not yet required
behavior.
Assuming the presence of -print was added to correct a historical pitfall that plagues novice users, it
is entirely upwards-compatible from the historical System V find utility. In its simplest form ( find
directory), it could be confused with the historical BSD fast find. The BSD developers agreed that adding
-print as a default expression was the correct decision and have added the fast find functionality within
a new utility called locate.
Historically, the -L option was implemented using the primary -follow. The -H and -L options were added
for two reasons. First, they offer a finer granularity of control and consistency with other programs
that walk file hierarchies. Second, the -follow primary always evaluated to true. As they were
historically really global variables that took effect before the traversal began, some valid expressions
had unexpected results. An example is the expression -print -o -follow. Because -print always evaluates
to true, the standard order of evaluation implies that -follow would never be evaluated. This was never
the case. Historical practice for the -follow primary, however, is not consistent. Some implementations
always follow symbolic links on the command line whether -follow is specified or not. Others follow
symbolic links on the command line only if -follow is specified. Both behaviors are provided by the -H
and -L options, but scripts using the current -follow primary would be broken if the -follow option is
specified to work either way.
Since the -L option resolves all symbolic links and the -type l primary is true for symbolic links that
still exist after symbolic links have been resolved, the command:
find -L . -type l
prints a list of symbolic links reachable from the current directory that do not resolve to accessible
files.
A feature of SVR4's find utility was the -exec primary's + terminator. This allowed filenames containing
special characters (especially <newline>s) to be grouped together without the problems that occur if such
filenames are piped to xargs. Other implementations have added other ways to get around this problem,
notably a -print0 primary that wrote filenames with a null byte terminator. This was considered here, but
not adopted. Using a null terminator meant that any utility that was going to process find's -print0
output had to add a new option to parse the null terminators it would now be reading.
The "-exec ... {} +" syntax adopted was a result of IEEE PASC Interpretation 1003.2 #210. It should be
noted that this is an incompatible change to the ISO/IEC 9899:1999 standard. For example, the following
command prints all files with a '-' after their name if they are regular files, and a '+' otherwise:
find / -type f -exec echo {} - ';' -o -exec echo {} + ';'
The change invalidates usage like this. Even though the previous standard stated that this usage would
work, in practice many did not support it and the standard developers felt it better to now state that
this was not allowable.
FUTURE DIRECTIONS
None.
SEE ALSO
Quoting , Pattern Matching Notation , Special Built-In Utilities , chmod() , pax , sh , test , the System
Interfaces volume of IEEE Std 1003.1-2001, getgrgid(), getpwuid(), stat()
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The
original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 FIND(P)