IRIX Base Documentation 2002 November/SGI IRIX Base Documentation 2002 November.iso/usr/share/catman/u_man/cat1/awk.z/awk

Text File | 2002-10-03 | 21.1 KB | 462 lines

aaaawwwwkkkk((((1111))))                                                                  aaaawwwwkkkk((((1111))))



NNNNAAAAMMMMEEEE
     aaaawwwwkkkk, nnnnaaaawwwwkkkk, ppppaaaawwwwkkkk  - pattern scanning and processing language

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
     aaaawwwwkkkk [----FFFF _r_e] [----vvvv _v_a_r=_v_a_l_u_e] [''''_p_r_o_g''''] [_f_i_l_e. . .]
     aaaawwwwkkkk [----FFFF _r_e] [----vvvv _v_a_r=_v_a_l_u_e] [----ffff _p_r_o_g_f_i_l_e] [_f_i_l_e. . .]

DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     NNNNOOOOTTTTEEEE:::: This version of awk has some incompatibilities with previous
     versions. See the COMPATIBILITY ISSUES section below for more detail.

     aaaawwwwkkkk and nnnnaaaawwwwkkkk use the old rrrreeeeggggeeeexxxxpppp(((()))) and ccccoooommmmppppiiiilllleeee(((()))) regular expression
     routines.  When the environment variable ____XXXXPPPPGGGG is equal to 1111 (one), ppppaaaawwwwkkkk
     is exec'ed which uses the newer rrrreeeeggggccccoooommmmpppp(((()))) and rrrreeeeggggeeeexxxxeeeecccc(((()))) routines which
     implement the Extended Regular Expression package.

     aaaawwwwkkkk scans each input _f_i_l_e for lines that match any of a set of patterns
     specified in _p_r_o_g.  The _p_r_o_g string must be enclosed in single quotes ('''')
     to protect it from the shell.  Patterns are arbitrary Boolean
     combinations of regular expressions and relational expressions.  For each
     pattern in _p_r_o_g there may be an associated action performed when a line
     of a _f_i_l_e matches the pattern.  The set of pattern-action statements may
     appear literally as _p_r_o_g or in a file specified with the ----ffff _p_r_o_g_f_i_l_e
     option.  Input files are read in order; if there are no files, the
     standard input is read.  The file name ---- means the standard input.

     aaaawwwwkkkk processes supplementary code set characters in pattern-action
     statements and comments, and recognizes supplementary code set characters
     as field separators (see below) according to the locale specified in the
     LLLLCCCC____CCCCTTTTYYYYPPPPEEEE environment variable [see LLLLAAAANNNNGGGG on eeeennnnvvvviiiirrrroooonnnn(5)].  In regular
     expressions, pattern searches are performed on characters, not bytes, as
     described on eeeedddd(1).

     Each input line is matched against the pattern portion of every pattern-
     action statement; the associated action is performed for each matched
     pattern.  Any _f_i_l_e of the form vvvvaaaarrrr=_v_a_l_u_e is treated as an assignment, not
     a filename.  If the environment variable ____XXXXPPPPGGGG is equal to 1111 (one), each
     such assignment is executed at the time it would have been opened if it
     were a filename. If the environment variable ____XXXXPPPPGGGG is not set, all
     assignments that appear before the first actual file are processed as if
     each was preceded by the ----vvvv opton. The option ----vvvv followed by vvvvaaaarrrr=_v_a_l_u_e is
     an assignment to be done before _p_r_o_g is executed; any number of ----vvvv
     options may be present.

     An input line is normally made up of fields separated by white space.
     (This default can be changed by using the FFFFSSSS built-in variable or the ----FFFF
     _r_e option.)  The fields are denoted $$$$1111, $$$$2222, ...; $$$$0000 refers to the entire
     line.

     A pattern-action statement has the form:





                                                                        PPPPaaaaggggeeee 1111






aaaawwwwkkkk((((1111))))                                                                  aaaawwwwkkkk((((1111))))



          _p_a_t_t_e_r_n {{{{ _a_c_t_i_o_n }}}}

     Either pattern or action may be omitted.  If there is no action with a
     pattern, the matching line is printed.  If there is no pattern with an
     action, the action is performed on every input line.  Pattern-action
     statements are separated by newlines or semicolons.

     As noted, patterns are arbitrary Boolean combinations ( !!!!, ||, &&&&&&&&, and
     parentheses) of relational expressions and regular expressions.  A
     relational expression is one of the following:

          _e_x_p_r_e_s_s_i_o_n _r_e_l_o_p _e_x_p_r_e_s_s_i_o_n
          _e_x_p_r_e_s_s_i_o_n _m_a_t_c_h_o_p _r_e_g_u_l_a_r__e_x_p_r_e_s_s_i_o_n
          _e_x_p_r_e_s_s_i_o_n iiiinnnn _a_r_r_a_y-_n_a_m_e
          ((((_e_x_p_r_e_s_s_i_o_n,,,,_e_x_p_r_e_s_s_i_o_n,,,, ...  )))) iiiinnnn _a_r_r_a_y-_n_a_m_e

     where a _r_e_l_o_p is any of the six relational operators in C, and a _m_a_t_c_h_o_p
     is either ~~~~ (contains) or !!!!~~~~ (does not contain).  An _e_x_p_r_e_s_s_i_o_n is an
     arithmetic expression, a relational expression, the special expression

          _v_a_r iiiinnnn _a_r_r_a_y

     or a Boolean combination of these.

     Regular expressions are as in eeeeggggrrrreeeepppp(1).  In patterns they must be
     surrounded by slashes.  Isolated regular expressions in a pattern apply
     to the entire line.  Regular expressions may also occur in relational
     expressions.  A pattern may consist of two patterns separated by a comma;
     in this case, the action is performed for all lines between an occurrence
     of the first pattern and the next occurrence of the second pattern.

     The special patterns BBBBEEEEGGGGIIIINNNN and EEEENNNNDDDD may be used to capture control before
     the first input line has been read and after the last input line has been
     read respectively.  These keywords do not combine with any other
     patterns.

     A regular expression may be used to separate fields by using the ----FFFF _r_e
     option or by assigning the expression to the built-in variable FS.  The
     default is to ignore leading blanks and to separate fields by blanks
     and/or tab characters.  However, if FS is assigned a value, leading
     blanks are no longer ignored.

     Other built-in variables include:

          AAAARRRRGGGGCCCC            command line argument count

          AAAARRRRGGGGVVVV            command line argument array

          EEEENNNNVVVVIIIIRRRROOOONNNN         array of environment variables; subscripts are names






                                                                        PPPPaaaaggggeeee 2222






aaaawwwwkkkk((((1111))))                                                                  aaaawwwwkkkk((((1111))))



          FFFFIIIILLLLEEEENNNNAAAAMMMMEEEE        name of the current input file

          FFFFNNNNRRRR             ordinal number of the current record in the current
                          file

          FFFFSSSS              input field separator regular expression (default
                          blank and tab)

          NNNNFFFF              number of fields in the current record

          NNNNRRRR              ordinal number of the current record

          OOOOFFFFMMMMTTTT            output format for numbers (default %%%%....6666gggg)

          OOOOFFFFSSSS             output field separator (default blank)

          OOOORRRRSSSS             output record separator (default new-line)

          RRRRSSSS              input record separator (default new-line)

          SSSSUUUUBBBBSSSSEEEEPPPP          separates multiple subscripts (default is 034)

     The field separators specified with the ----FFFF option or with the variables
     OOOOFFFFSSSS, OOOORRRRSSSS, and FFFFSSSS may be supplementary code set characters.

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

          iiiiffff ( _e_x_p_r_e_s_s_i_o_n ) _s_t_a_t_e_m_e_n_t [ eeeellllsssseeee _s_t_a_t_e_m_e_n_t ]
          wwwwhhhhiiiilllleeee ( _e_x_p_r_e_s_s_i_o_n ) _s_t_a_t_e_m_e_n_t
          ddddoooo _s_t_a_t_e_m_e_n_t wwwwhhhhiiiilllleeee ( _e_x_p_r_e_s_s_i_o_n )
          ffffoooorrrr ( _e_x_p_r_e_s_s_i_o_n ; _e_x_p_r_e_s_s_i_o_n ; _e_x_p_r_e_s_s_i_o_n ) _s_t_a_t_e_m_e_n_t
          ffffoooorrrr ( _v_a_r iiiinnnn _a_r_r_a_y ) _s_t_a_t_e_m_e_n_t
          ddddeeeelllleeeetttteeee _a_r_r_a_y[_s_u_b_s_c_r_i_p_t] #delete an array element
          bbbbrrrreeeeaaaakkkk
          ccccoooonnnnttttiiiinnnnuuuueeee
          { [ _s_t_a_t_e_m_e_n_t ] ... }
          _e_x_p_r_e_s_s_i_o_n     # commonly variable = expression
          pppprrrriiiinnnntttt [ _e_x_p_r_e_s_s_i_o_n-_l_i_s_t ] [ >_e_x_p_r_e_s_s_i_o_n ]
          pppprrrriiiinnnnttttffff _f_o_r_m_a_t [ , _e_x_p_r_e_s_s_i_o_n-_l_i_s_t ] [ >_e_x_p_r_e_s_s_i_o_n ]
          nnnneeeexxxxtttt      # skip remaining patterns on this input line
          eeeexxxxiiiitttt [eeeexxxxpppprrrr]    # skip the rest of the input; exit status is expr
          rrrreeeettttuuuurrrrnnnn [eeeexxxxpppprrrr]

     Statements are terminated by semicolons, new-lines, or right braces.  An
     empty expression-list stands for the whole input line.  Expressions take
     on string or numeric values as appropriate, and are built using the
     operators ++++, ----, ****, ////, %%%%, ^^^^ and concatenation (indicated by a blank).  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 or zero.  Array
     subscripts may be any string, not necessarily numeric; this allows for a



                                                                        PPPPaaaaggggeeee 3333






aaaawwwwkkkk((((1111))))                                                                  aaaawwwwkkkk((((1111))))



     form of associative memory.  Multiple subscripts such as [[[[iiii,,,,jjjj,,,,kkkk]]]] are
     permitted; the constituents are concatenated, separated by the value of
     SSSSUUUUBBBBSSSSEEEEPPPP.  String constants are quoted (""""""""), with the usual C escapes
     recognized within.

     A comment consists of any characters beginning with the number sign
     character and terminated by, but excluding the next occurrence of, a
     newline character. Comments will have no effect, except to delimit
     statements.

     The pppprrrriiiinnnntttt statement prints its arguments on the standard output, or on a
     file if >>>>_e_x_p_r_e_s_s_i_o_n is present, or on a pipe if | _c_m_d is present.  The
     arguments are separated by the current output field separator and
     terminated by the output record separator.  The pppprrrriiiinnnnttttffff statement formats
     its expression list according to the format (see pppprrrriiiinnnnttttffff(3S)).  The
     built-in function cccclllloooosssseeee(_e_x_p_r) closes the file or pipe _e_x_p_r.

     The mathematical functions:  aaaattttaaaannnn2222, ccccoooossss, eeeexxxxpppp, lllloooogggg, ssssiiiinnnn, ssssqqqqrrrrtttt, are built-
     in.

     Other built-in functions include:

     ggggssssuuuubbbb(_f_o_r, _r_e_p_l, _i_n)
               behaves like ssssuuuubbbb (see below), except that it replaces
               successive occurrences of the regular expression (like the eeeedddd
               global substitute command).

     iiiinnnnddddeeeexxxx((((_s,,,, _t))))
               returns the position in string _s where string _t first occurs,
               or 0 if it does not occur at all.

     iiiinnnntttt       truncates to an integer value.

     lllleeeennnnggggtttthhhh((((_s)))) returns the length in bytes of its argument taken as a string,
               or of the whole line if there is no argument.

     mmmmaaaattttcccchhhh((((_s,,,, _r_e))))
               returns the position in string _s where the regular expression
               _r_e occurs, or 0 if it does not occur at all.  RRRRSSSSTTTTAAAARRRRTTTT is set to
               the starting position (which is the same as the returned
               value), and RRRRLLLLEEEENNNNGGGGTTTTHHHH is set to the length of the matched string.

     rrrraaaannnndddd      random number on (0, 1).

     sssspppplllliiiitttt((((_s,,,, _a,,,, _f_s))))
               splits the string _s into array elements _a[_1], _a[_2], _a[_n], and
               returns _n.  The separation is done with the regular expression
               _f_s or with the field separator FFFFSSSS if _f_s is not given.

     ssssrrrraaaannnndddd     sets the seed for rrrraaaannnndddd





                                                                        PPPPaaaaggggeeee 4444






aaaawwwwkkkk((((1111))))                                                                  aaaawwwwkkkk((((1111))))



     sssspppprrrriiiinnnnttttffff((((_f_m_t,,,, _e_x_p_r,,,, _e_x_p_r,,,,...))))
               formats the expressions according to the pppprrrriiiinnnnttttffff(3S) format
               given by _f_m_t and returns the resulting string.

     ssssuuuubbbb(_f_o_r, _r_e_p_l, _i_n)
               substitutes the string _r_e_p_l in place of the first instance of
               the regular expression _f_o_r in string _i_n and returns the number
               of substitutions.  If _i_n is omitted, aaaawwwwkkkk substitutes in the
               current record ($$$$0000).

     ssssuuuubbbbssssttttrrrr(_s, _m, _n)
               returns the _n-byte substring of _s that begins at position _m.

     ttttoooolllloooowwwweeeerrrr(_s)
               converts all upper-case alphabetic characters in string _s to
               lower-case.  Numbers and other characters are not affected.

     ttttoooouuuuppppppppeeeerrrr(_s)
               converts all lower-case alphabetic characters in string _s to
               upper-case. Numbers and other characters are not affected.


     The input/output built-in functions are:

     cccclllloooosssseeee((((_f_i_l_e_n_a_m_e))))
               closes the file or pipe named _f_i_l_e_n_a_m_e.

     _c_m_d |||| ggggeeeettttlllliiiinnnneeee
               pipes the output of _c_m_d into ggggeeeettttlllliiiinnnneeee; each successive call to
               _g_e_t_l_i_n_e returns the next line of output from _c_m_d.

     ggggeeeettttlllliiiinnnneeee   sets $$$$0000 to the next input record from the current input file.

     ggggeeeettttlllliiiinnnneeee <<<<_f_i_l_e
               sets $$$$0000 to the next record from _f_i_l_e.

     ggggeeeettttlllliiiinnnneeee _x sets variable _x instead.

     ggggeeeettttlllliiiinnnneeee _x <<<<_f_i_l_e
               sets _x from the next record of _f_i_l_e.

     ssssyyyysssstttteeeemmmm((((_c_m_d))))
               executes _c_m_d and returns its exit status.

     All forms of ggggeeeettttlllliiiinnnneeee return 1 for successful input, 0 for end of file,
     and -1 for an error.

     aaaawwwwkkkk also provides user-defined functions.  Such functions may be defined
     (in the pattern position of a pattern-action statement) as






                                                                        PPPPaaaaggggeeee 5555






aaaawwwwkkkk((((1111))))                                                                  aaaawwwwkkkk((((1111))))



          _ffff_uuuu_nnnn_cccc_tttt_iiii_oooo_nnnn _n_a_m_e_((((_a_r_g_s_,,,,..._)))) _{{{{ _s_t_m_t_s _}}}}

     Function arguments are passed by value if scalar and by reference if
     array name.  Argument names are local to the function; all other variable
     names are global.  Function calls may be nested and functions may be
     recursive.  The rrrreeeettttuuuurrrrnnnn statement may be used to return a value.

EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS
     Print lines longer than 72 characters:

          length > 72

     Print first two fields in opposite order:

          { print $2, $1 }

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


     Add up first column, print sum and average:

          { s += $1 }
          END { print "sum is", s, " average is", s/NR }

     Print fields in reverse order:

          { for (i = NF; i > 0; --i) print $i }

     Print all lines between start/stop pairs:

          /start/, /stop/

     Print all lines whose first field is different from previous one:

          $1 != prev { print; prev = $1 }

     Simulate eeeecccchhhhoooo(1):

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

     Print a file, filling in page numbers starting at 5:






                                                                        PPPPaaaaggggeeee 6666






aaaawwwwkkkk((((1111))))                                                                  aaaawwwwkkkk((((1111))))



          /Page/ { $2 = n++; }
          { print }

     Assuming this program is in a file named pppprrrroooogggg, the following command line
     prints the file iiiinnnnppppuuuutttt numbering its pages starting at 5:  awk -f prog n=5
     input.

FFFFIIIILLLLEEEESSSS
     /usr/lib/locale/locale/LC_MESSAGES/uxawk
          language-specific message file (see LLLLAAAANNNNGGGG on eeeennnnvvvviiiirrrroooonnnn(5))

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     ooooaaaawwwwkkkk(1), eeeeggggrrrreeeepppp(1), ggggrrrreeeepppp(1), lllleeeexxxx(1), ppppeeeerrrrllll(1), sssseeeedddd(1), pppprrrriiiinnnnttttffff(3S)
     A. V. Aho, B. W. Kernighan, P. J. Weinberger, _T_h_e _a_w_k _P_r_o_g_r_a_m_m_i_n_g
     _L_a_n_g_u_a_g_e Addison-Wesley, 1988

NNNNOOOOTTTTEEEESSSS aaaannnndddd CCCCOOOOMMMMPPPPAAAATTTTIIIIBBBBIIIILLLLIIIITTTTYYYY IIIISSSSSSSSUUUUEEEESSSS
     aaaawwwwkkkk is a newer version that provides capabilities unavailable in previous
     versions.  See ooooaaaawwwwkkkk(1) for the older version.

     Input white space is not preserved on output if fields are involved.

     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 the null string ("""""""") to it.

     The following regular expressions are no longer accepted:

         ////[[[[]]]]////     ////[[[[^^^^]]]]////      ////[[[[\\\\]]]]]]]]////


























                                                                        PPPPaaaaggggeeee 7777