Return to awk CVS log

Up to [MW Coherent from dump] / coherent / a / usr / man / COHERENT

Annotation of coherent/a/usr/man/COHERENT/awk, revision 1.1

1.1     ! root        1: 
        !             2: 
        !             3: awk                          Command                          awk
        !             4: 
        !             5: 
        !             6: 
        !             7: 
        !             8: Pattern-scanning language
        !             9: 
        !            10: aawwkk [-yy][-FF _c][-ff _p_r_o_g_f_i_l_e][_p_r_o_g][_f_i_l_e ...]
        !            11: 
        !            12: awk is  a general-purpose language designed  for processing input
        !            13: data.  Its  features allow  you to  write programs that  scan for
        !            14: patterns, produce reports, and filter relevant information from a
        !            15: mass of  input data.   It acts on  each input file  following the
        !            16: commands you  write into an awk program.   awk reads the standard
        !            17: input if no file is specified, which allows it to act as a filter
        !            18: in a pipeline; the file name `-' means the standard input.
        !            19: 
        !            20: You can  specify the program either as  an argument prog (usually
        !            21: enclosed  in quotation  marks  to prevent  interpretation by  the
        !            22: shell sh) or in the form -f progfile, where progfile contains the
        !            23: awk program.  If no -f option appears, the first non-option argu-
        !            24: ment is the awk program prog.
        !            25: 
        !            26: The  option  flag -y  specifies  that  any lower-case  alphabetic
        !            27: character in  a regular expression pattern  should match both it-
        !            28: self and the  corresponding upper-case letter.  This is identical
        !            29: to the  matching found in the  pattern-matching program grep with
        !            30: the -y option.
        !            31: 
        !            32: awk views its input as  a sequence of records, each consisting of
        !            33: zero or  more fields.  By default,  newlines separate records and
        !            34: white space  (spaces or tabs)  separates fields.  The  option -Fc
        !            35: changes the input field separator characters to the characters in
        !            36: the  string c.   An awk  program  can also  change the  field and
        !            37: record  separators.  The  program can access  the values  of each
        !            38: field and the entire record through built-in variables.
        !            39: 
        !            40: For  details on  the construction  of  awk programs,  consult the
        !            41: tutorial to  aawwkk that  appears in  this manual.  Briefly,  an awk
        !            42: program consists of one  or more lines, each containing a pattern
        !            43: or an action, or both.  A pattern determines whether awk performs
        !            44: the associated  action.  It  may consist of  regular expressions,
        !            45: line ranges, boolean combinations of variables, and beginning and
        !            46: end of  input-text predicates.  If  no pattern is  specified, awk
        !            47: executes the action (the pattern matches by default).
        !            48: 
        !            49: An action  is enclosed  in braces.  The  syntax of actions  is C-
        !            50: like, and consists  of simple and compound statements constructed
        !            51: from  constants (numbers,  strings), input  fields,  built-in and
        !            52: user-defined variables, and  built-in functions.  If an action is
        !            53: missing, awk prints the entire input record (line).
        !            54: 
        !            55: Unlike lex or yacc, awk does not compile programs into an execut-
        !            56: able image, but interprets them directly.  Thus, awk is ideal for
        !            57: quickly-implemented, one-shot efforts.
        !            58: 
        !            59: ***** Examples *****
        !            60: 
        !            61: The following  examples illustrate  the economy of  expression of
        !            62: 
        !            63: 
        !            64: COHERENT Lexicon                                           Page 1
        !            65: 
        !            66: 
        !            67: 
        !            68: 
        !            69: awk                          Command                          awk
        !            70: 
        !            71: 
        !            72: 
        !            73: awk programs.
        !            74: 
        !            75: The  first  example   prints  all  lines  containing  the  string
        !            76: ``COHERENT'' (identical to ggrreepp CCOOHHEERREENNTT):
        !            77: 
        !            78: 
        !            79:         /COHERENT/
        !            80: 
        !            81: 
        !            82: The  built-in variable  NR  is the  number of  the current  input
        !            83: record,  so the  following program prints  the number  of records
        !            84: (lines) in the input stream.
        !            85: 
        !            86: 
        !            87:         END     { print NR }
        !            88: 
        !            89: 
        !            90: The built-in  variable $3 gives  the value of the  third field of
        !            91: the current record, so the following program sums the elements in
        !            92: column three of an input table and prints the total:
        !            93: 
        !            94: 
        !            95:                 { sum += $3 }
        !            96:         END     { print sum }
        !            97: 
        !            98: 
        !            99: ***** See Also *****
        !           100: 
        !           101: commands, grep, lex, sed, yacc
        !           102: _I_n_t_r_o_d_u_c_t_i_o_n _t_o _t_h_e _a_w_k _L_a_n_g_u_a_g_e
        !           103: 
        !           104: ***** Notes *****
        !           105: 
        !           106: There is  no way to  have a null  field, such as  is necessary to
        !           107: describe the colon-separated fields in /etc/passwd.
        !           108: 
        !           109: awk converts  between strings and  numbers automatically.  Adding
        !           110: zero  to a  string  forces awk  to  treat it  as  a number;  con-
        !           111: catenating "" to a number forces awk to treat it as a string.
        !           112: 
        !           113: 
        !           114: 
        !           115: 
        !           116: 
        !           117: 
        !           118: 
        !           119: 
        !           120: 
        !           121: 
        !           122: 
        !           123: 
        !           124: 
        !           125: 
        !           126: 
        !           127: 
        !           128: 
        !           129: 
        !           130: COHERENT Lexicon                                           Page 2
        !           131: 
        !           132: 

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.