Provided by: original-awk_2022-09-12-1_amd64 bug

NAME

       original-awk - pattern-directed scanning and processing language

SYNOPSIS

       original-awk [ -F fs ] [ -v var=value ] [ 'prog' | -f progfile ] [ file ...  ]

DESCRIPTION

       Awk  (original-awk)  scans  each  input file for lines that match any of a set of patterns
       specified literally in prog or in one or more files specified as -f progfile.   With  each
       pattern  there  can  be  an associated action that will be performed when a line of a file
       matches the pattern.  Each line is matched against the pattern portion of  every  pattern-
       action  statement;  the associated action is performed for each matched pattern.  The file
       name - means the standard input.  Any  file  of  the  form  var=value  is  treated  as  an
       assignment,  not  a  filename, and is executed at the time it would have been opened if it
       were a filename.  The option -v followed by var=value is an assignment to be  done  before
       prog  is  executed; any number of -v options may be present.  The -F fs option defines the
       input field separator to be the regular expression fs.

       An input line is normally made up of fields separated by white space, or  by  the  regular
       expression  FS.   The  fields are denoted $1, $2, ..., while $0 refers to the entire line.
       If FS is null, the input line is split into one field per character.

       A pattern-action statement has the form:

              pattern { action }

       A missing { action } means print the line; a missing  pattern  always  matches.   Pattern-
       action statements are separated by newlines or semicolons.

       An action is a sequence of statements.  A statement can be one of the following:

              if( expression ) statement [ else statement ]
              while( expression ) statement
              for( expression ; expression ; expression ) statement
              for( var in array ) statement
              do statement while( expression )
              break
              continue
              { [ statement ... ] }
              expression              # commonly var = expression
              print [ expression-list ] [ > expression ]
              printf format [ , expression-list ] [ > expression ]
              return [ expression ]
              next                    # skip remaining patterns on this input line
              nextfile                # skip rest of this file, open next, start at top
              delete array[ expression ]# delete an array element
              delete array            # delete all elements of array
              exit [ expression ]     # exit immediately; status is expression

       Statements  are  terminated by semicolons, newlines or right braces.  An empty expression-
       list stands for $0.  String constants are quoted " ", with the usual C escapes  recognized
       within.   Expressions take on string or numeric values as appropriate, and are built using
       the operators + - * / % ^ (exponentiation), and concatenation (indicated by white  space).
       The  operators  !  ++  --  +=  -=  *=  /=  %=  ^= > >= < <= == != ?: are also available in
       expressions.   Variables  may  be  scalars,  array  elements  (denoted  x[i])  or  fields.
       Variables  are  initialized  to  the null string.  Array subscripts may be any string, not
       necessarily numeric; this allows for a form of associative  memory.   Multiple  subscripts
       such  as  [i,j,k] are permitted; the constituents are concatenated, separated by the value
       of SUBSEP.

       The print statement prints its arguments on the standard output (or on a file if > file or
       >>  file  is  present  or  on a pipe if | cmd is present), separated by the current output
       field separator, and terminated by the output record  separator.   file  and  cmd  may  be
       literal   names  or  parenthesized  expressions;  identical  string  values  in  different
       statements denote the same open file.  The printf statement formats  its  expression  list
       according  to  the  format  (see printf(3)).  The built-in function close(expr) closes the
       file or pipe expr.  The built-in function fflush(expr) flushes any buffered output for the
       file or pipe expr.

       The mathematical functions atan2, cos, exp, log, sin, and sqrt are built in.  Other built-
       in functions:

       length  the length of its argument taken as a string, number of elements in an  array  for
               an array argument, or length of $0 if no argument.
       rand    random number on [0,1).
       srand   sets seed for rand and returns the previous seed.
       int     truncates to an integer value.
       substr(s, m [, n])
               the n-character substring of s that begins at position m counted from 1.  If no n,
               use the rest of the string.
       index(s, t)
               the position in s where the string t occurs, or 0 if it does not.
       match(s, r)
               the position in s where the regular expression r occurs, or 0 if it does not.  The
               variables  RSTART  and  RLENGTH  are set to the position and length of the matched
               string.
       split(s, a [, fs])
               splits the string s into array elements a[1], a[2], ..., a[n], and returns n.  The
               separation  is  done with the regular expression fs or with the field separator FS
               if fs is not given.  An empty string as field separator splits the string into one
               array element per character.
       sub(r, t [, s])
               substitutes  t  for the first occurrence of the regular expression r in the string
               s.  If s is not given, $0 is used.
       gsub(r, t [, s])
               same as sub except that all occurrences of the regular  expression  are  replaced;
               sub and gsub return the number of replacements.
       sprintf(fmt, expr, ...)
               the  string  resulting from formatting expr ...  according to the printf(3) format
               fmt.
       system(cmd)
               executes cmd and returns its exit status. This will be -1 upon error,  cmd's  exit
               status upon a normal exit, 256 + sig upon death-by-signal, where sig is the number
               of the murdering signal, or 512 + sig if there was a core dump.
       tolower(str)
               returns a  copy  of  str  with  all  upper-case  characters  translated  to  their
               corresponding lower-case equivalents.
       toupper(str)
               returns  a  copy  of  str  with  all  lower-case  characters  translated  to their
               corresponding upper-case equivalents.

       The ``function'' getline sets $0 to the next input record from  the  current  input  file;
       getline  <  file sets $0 to the next record from file.  getline x sets variable x instead.
       Finally, cmd | getline pipes the output of cmd into getline; each call of getline  returns
       the next line of output from cmd.  In all cases, getline returns 1 for a successful input,
       0 for end of file, and -1 for an error.

       Patterns are arbitrary Boolean combinations (with ! ||  &&)  of  regular  expressions  and
       relational  expressions.   Regular  expressions  are  as  in egrep; see grep(1).  Isolated
       regular expressions in a pattern apply to the entire line.  Regular expressions  may  also
       occur in relational expressions, using the operators ~ and !~.  /re/ is a constant regular
       expression; any string (constant or variable) may be used as a regular expression,  except
       in the position of an isolated regular expression in a pattern.

       A  pattern  may  consist of two patterns separated by a comma; in this case, the action is
       performed for all lines from an occurrence of the first pattern though  an  occurrence  of
       the second.

       A relational expression is one of the following:

              expression matchop regular-expression
              expression relop expression
              expression in array-name
              (expr,expr,...) in array-name

       where  a  relop  is  any  of  the six relational operators in C, and a matchop is either ~
       (matches) or !~ (does not match).  A conditional is an arithmetic expression, a relational
       expression, or a Boolean combination of these.

       The  special  patterns BEGIN and END may be used to capture control before the first input
       line is read and after the last.  BEGIN and END do not combine with other patterns.   They
       may appear multiple times in a program and execute in the order they are read by awk.

       Variable names with special meanings:

       ARGC      argument count, assignable.
       ARGV      argument array, assignable; non-null members are taken as filenames.
       CONVFMT   conversion format used when converting numbers (default %.6g).
       ENVIRON   array of environment variables; subscripts are names.
       FILENAME  the name of the current input file.
       FNR       ordinal number of the current record in the current file.
       FS        regular expression used to separate fields; also settable by option -Ffs.
       NF        number of fields in the current record.
       NR        ordinal number of the current record.
       OFMT      output format for numbers (default %.6g).
       OFS       output field separator (default space).
       ORS       output record separator (default newline).
       RLENGTH   the length of a string matched by match.
       RS        input  record  separator  (default  newline).   If  empty,  blank lines separate
                 records.  If  more  than  one  character  long,  RS  is  treated  as  a  regular
                 expression, and records are separated by text matching the expression.
       RSTART    the start position of a string matched by match.
       SUBSEP    separates multiple subscripts (default 034).

       Functions may be defined (at the position of a pattern-action statement) thus:

              function foo(a, b, c) { ...; return x }

       Parameters  are passed by value if scalar and by reference if array name; functions may be
       called recursively.  Parameters are local to the function; all other variables are global.
       Thus  local  variables  may  be  created  by  providing  excess parameters in the function
       definition.

ENVIRONMENT VARIABLES

       If POSIXLY_CORRECT is set in the environment, then awk follows the POSIX rules for sub and
       gsub with respect to consecutive backslashes and ampersands.

EXAMPLES

       length($0) > 72
              Print lines longer than 72 characters.

       { print $2, $1 }
              Print first two fields in opposite order.

       BEGIN { FS = ",[ \t]*|[ \t]+" }
             { print $2, $1 }
              Same, with input fields separated by comma and/or spaces and tabs.

            { s += $1 }
       END  { print "sum is", s, " average is", s/NR }
              Add up first column, print sum and average.

       /start/, /stop/
              Print all lines between start/stop pairs.

       BEGIN     {    # Simulate echo(1)
            for (i = 1; i < ARGC; i++) printf "%s ", ARGV[i]
            printf "\n"
            exit }

SEE ALSO

       grep(1), lex(1), sed(1)
       A.  V.  Aho,  B.  W.  Kernighan,  P. J. Weinberger, The AWK Programming Language, Addison-
       Wesley, 1988.  ISBN 0-201-07981-X.

BUGS

       There are no explicit conversions between numbers and strings.  To force an expression  to
       be  treated  as a number add 0 to it; to force it to be treated as a string concatenate ""
       to it.

       The scope rules for variables in functions are a botch; the syntax is worse.

       Only eight-bit characters sets are handled correctly.

UNUSUAL FLOATING-POINT VALUES

       Awk was designed before IEEE  754  arithmetic  defined  Not-A-Number  (NaN)  and  Infinity
       values, which are supported by all modern floating-point hardware.

       Because  awk  uses  strtod(3)  and  atof(3)  to  convert string values to double-precision
       floating-point values, modern C libraries also convert strings starting with inf  and  nan
       into  infinity  and  NaN values respectively.  This led to strange results, with something
       like this:

       echo nancy | awk '{ print $1 + 0 }'

       printing nan instead of zero.

       Awk now follows GNU AWK, and prefilters string values before attempting to convert them to
       numbers, as follows:

       Hexadecimal values
              Hexadecimal values (allowed since C99) convert to zero, as they did prior to C99.

       NaN values
              The  two  strings  +nan  and  -nan (case independent) convert to NaN. No others do.
              (NaNs can have signs.)

       Infinity values
              The two strings +inf and -inf (case independent) convert to positive  and  negative
              infinity, respectively.  No others do.

                                                                                  ORIGINAL-AWK(1)