awk.cheat.sheet.txt

.-----------------------------------------------------------------------.
|                                                                       |
|                              AWK Cheat Sheet                          |
|                                                                       |
'-----------------------------------------------------------------------'
| Peteris Krumins (peter@catonmat.net), 2007.08.22                      |
| http://www.catonmat.net  -  good coders code, great reuse             |
'-----------------------------------------------------------------------'


 ===================== Predefined Variable Summary =====================

.-------------+-----------------------------------.---------------------.
|             |                                   |      Support:       |
| Variable    | Description                       '-----.-------.-------'
|             |                                   | AWK | NAWK  | GAWK  |
'-------------+-----------------------------------+-----+-------+-------'
| FS          | Input Field Separator, a space by |  +  |   +   |   +   |
|             | default.                          |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| OFS         | Output Field Separator, a space   |  +  |   +   |   +   |
|             | by default.                       |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| NF          | The Number of Fields in the       |  +  |   +   |   +   |
|             | current input record.             |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| NR          | The total Number of input Records |  +  |   +   |   +   |
|             | seen so far.                      |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| RS          | Record Separator, a newline by    |  +  |   +   |   +   |
|             | default.                          |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| ORS         | Output Record Separator, a        |  +  |   +   |   +   |
|             | newline by default.               |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| FILENAME    | The name of the current input     |     |       |       |
|             | file. If no files are specified   |     |       |       |
|             | on the command line, the value of |     |       |       |
|             | FILENAME is "-". However,         |  +  |   +   |   +   |
|             | FILENAME is undefined inside the  |     |       |       |
|             | BEGIN block (unless set by        |     |       |       |
|             | getline).                         |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| ARGC        | The number of command line        |     |       |       |
|             | arguments (does not include       |     |       |       |
|             | options to gawk, or the program   |  -  |   +   |   +   |
|             | source). Dynamically changing the |     |       |       |
|             | contents of ARGV control the      |  -  |   +   |   +   |
|             | files used for data.              |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| ARGV        | Array of command line arguments.  |     |       |       |
|             | The array is indexed from 0 to    |  -  |   +   |   +   |
|             | ARGC - 1.                         |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| ARGIND      | The index in ARGV of the current  |  -  |   -   |   +   |
|             | file being processed.             |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| BINMODE     | On non-POSIX systems, specifies   |     |       |       |
|             | use of "binary" mode for all file |     |       |       |
|             | I/O.Numeric values of 1, 2, or 3, |     |       |       |
|             | specify that input files, output  |     |       |       |
|             | files, or all files, respectively,|     |       |       |
|             | should use binary I/O. String     |     |       |       |
|             | values of  "r", or "w" specify    |  -  |   -   |   +   |
|             | that input files, or output files,|     |       |       |
|             | respectively, should use binary   |     |       |       |
|             | I/O. String values of "rw" or     |     |       |       |
|             |  "wr" specify that all files      |     |       |       |
|             | should use binary I/O. Any other  |     |       |       |
|             | string value is treated as "rw",  |     |       |       |
|             | but generates a warning message.  |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| CONVFMT     | The CONVFMT variable is used to   |     |       |       |
|             | specify the format when           |  -  |   -   |   +   |
|             | converting a number to a string.  |     |       |       |
|             | Default: "%.6g"                   |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| ENVIRON     | An array containing the values    |  -  |   -   |   +   |
|             | of the current environment.       |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| ERRNO       | If a system error occurs either   |     |       |       |
|             | doing a redirection for getline,  |     |       |       |
|             | during a read for getline, or     |     |       |       |
|             | during a close(), then ERRNO will |  -  |   -   |   +   |
|             | contain a string describing the   |     |       |       |
|             | error. The value is subject to    |     |       |       |
|             | translation in non-English locales.     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| FIELDWIDTHS | A white-space separated list of   |     |       |       |
|             | fieldwidths. When set, gawk       |     |       |       |
|             | parses the input into fields of   |  -  |   -   |   +   |
|             | fixed width, instead of using the |     |       |       |
|             | value of the FS variable as the   |     |       |       |
|             | field separator.                  |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| FNR         | Contains number of lines read,    |  -  |   +   |   +   |
|             | but is reset for each file read.  |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| IGNORECASE  | Controls the case-sensitivity of  |     |       |       |
|             | all regular expression and string |     |       |       |
|             | operations. If IGNORECASE has a   |     |       |       |
|             | non-zero value, then string       |     |       |       |
|             | comparisons and pattern matching  |     |       |       |
|             | in rules, field splitting         |     |       |       |
|             | with FS, record separating        |     |       |       |
|             | with RS, regular expression       |     |       |       |
|             | matching with ~ and !~, and the   |  -  |   -   |   +   |
|             | gensub(), gsub(), index(),        |     |       |       |
|             | match(), split(), and sub()       |     |       |       |
|             | built-in functions all ignore     |     |       |       |
|             | case when doing regular           |     |       |       |
|             | expression operations.            |     |       |       |
|             | NOTE: Array subscripting is not   |     |       |       |
|             | affected. However, the asort()    |     |       |       |
|             | and asorti() functions are        |     |       |       |
|             | affected                          |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| LINT        | Provides dynamic control of the   |     |       |       |
|             | --lint option from within an AWK  |  -  |   -   |   +   |
|             | program. When true, gawk prints   |     |       |       |
|             | lint warnings.                    |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| OFMT        | The default output format for     |  -  |   +   |   +   |
|             | numbers. Default: "%.6g"          |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| PROCINFO    | The elements of this array        |     |       |       |
|             | provide access to information     |     |       |       |
|             | about the running AWK program.    |     |       |       |
|             | PROCINFO["egid"]:                 |     |       |       |
|             | the value of the getegid(2)       |     |       |       |
|             | system call.                      |     |       |       |
|             | PROCINFO["euid"]:                 |     |       |       |
|             | the value of the geteuid(2)       |     |       |       |
|             | system call.                      |     |       |       |
|             | PROCINFO["FS"]:                   |     |       |       |
|             | "FS" if field splitting with FS   |     |       |       |
|             | is in effect, or "FIELDWIDTHS"    |     |       |       |
|             | if field splitting with           |     |       |       |
|             | FIELDWIDTHS is in effect.         |     |       |       |
|             | PROCINFO["gid"]:                  |  -  |   -   |   +   |
|             | the value of the getgid(2) system |     |       |       |
|             | call.                             |     |       |       |
|             | PROCINFO["pgrpid"]:               |     |       |       |
|             | the process group ID of the       |     |       |       |
|             | current process.                  |     |       |       |
|             | PROCINFO["pid"]:                  |     |       |       |
|             | the process ID of the current     |     |       |       |
|             | process.                          |     |       |       |
|             | PROCINFO["ppid"]:                 |     |       |       |
|             | the parent process ID of the      |     |       |       |
|             | current process.                  |     |       |       |
|             | PROCINFO["uid"]                   |     |       |       |
|             | the value of the getuid(2) system |     |       |       |
|             | call.                             |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| RT          | The record terminator. Gawk sets  |     |       |       |
|             | RT to the input text that matched |  -  |   -   |   +   |
|             | the character or regular          |     |       |       |
|             | expression specified by RS.       |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| RSTART      | The index of the first character  |  -  |   +   |   +   |
|             | matched by match(); 0 if no match.|     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| RLENGTH     | The length of the string matched  |  -  |   +   |   +   |
|             | by match(); -1 if no match.       |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| SUBSEP      | The character used to separate    |     |       |       |
|             | multiple subscripts in array      |     |       |       |
|             | elements.Default: "\034"          |  -  |   +   |   +   |
|             | (non-printable character,         |     |       |       |
|             | dec: 28, hex: 1C)                 |     |       |       |
'-------------+-----------------------------------+-----+-------+-------'
| TEXTDOMAIN  | The text domain of the AWK        |     |       |       |
|             | program; used to find the         |  -  |   -   |   +   |
|             | localized translations for the    |     |       |       |
|             | program's strings.                |     |       |       |
'-------------'-----------------------------------'-----'-------'-------'


 ============================ I/O Statements ===========================

.---------------------.-------------------------------------------------.
|                     |                                                 |
| Statement           | Description                                     |
|                     |                                                 |
'---------------------+-------------------------------------------------'
| close(file [, how]) | Close file, pipe or co-process. The optional    |
|                     | how should only be used when closing one end of |
|                     | a two-way pipe to a co-process. It must be a    |
|                     | string value, either "to" or "from".            |
'---------------------+-------------------------------------------------'
| getline             | Set $0 from next input record; set NF, NR, FNR. |
|                     | Returns 0 on EOF and –1 on an error. Upon an    |
|                     | error, ERRNO contains a string describing the   |
|                     | problem.                                        |
'---------------------+-------------------------------------------------'
| getline <file       | Set $0 from next record of file; set NF.        |
'---------------------+-------------------------------------------------'
| getline var         | Set var from next input record; set NR, FNR.    |
'---------------------+-------------------------------------------------'
| getline var <file   | Set var from next record of file.               |
'---------------------+-------------------------------------------------'
| command |           | Run command piping the output either into $0 or |
|   getline [var]     | var, as above. If using a pipe or co-process    |
|                     | to getline, or from print or printf within a    |
|                     | loop, you must use close() to create new        |
|                     | instances                                       |
'---------------------+-------------------------------------------------'
| command |&          | Run command as a co-process piping the output   |
|   getline [var]     | either into $0 or var, as above.  Co-processes  |
|                     | are a gawk extension.                           |
'---------------------+-------------------------------------------------'
| next                | Stop processing the current input record.       |
|                     | The next input record is read and processing    |
|                     | starts over with the first pattern in the AWK   |
|                     | program. If the end of the input data is        |
|                     | reached, the END block(s), if any, are executed.|
'---------------------+-------------------------------------------------'
| nextfile            | Stop processing the current input file. The     |
|                     | next input record read comes from the next      |
|                     | input file. FILENAME and ARGIND are updated,    |
|                     | FNR is reset to 1, and processing starts over   |
|                     | with the first pattern in the AWK program. If   |
|                     | the end of the input data is reached, the END   |
|                     | block(s), are executed.                         |
'---------------------+-------------------------------------------------'
| print               | Prints the current record. The output record is |
|                     | terminated with the value of the ORS variable.  |
'---------------------+-------------------------------------------------'
| print expr-list     | Prints expressions. Each expression is          |
|                     | separated by the value of the OFS variable.     |
|                     | The output record is terminated with the value  |
|                     | of the ORS variable.                            |
'---------------------+-------------------------------------------------'
| print expr-list     | Prints expressions on file. Each expression is  |
|   >file             | separated by the value of the OFS variable. The |
|                     | output record is terminated with the value of   |
|                     | the ORS variable.                               |
'---------------------+-------------------------------------------------'
| printf fmt,         | Format and print.                               |
|   expr-list         |                                                 |
'---------------------+-------------------------------------------------'
| printf fmt,         | Format and print on file.                       |
|   expr-list >file   |                                                 |
'---------------------+-------------------------------------------------'
| system(cmd-line)    | Execute the command cmd-line, and return the    |
|                     | exit status.                                    |
'---------------------+-------------------------------------------------'
| fflush([file])      | Flush any buffers associated with the open      |
|                     | output file or pipe file. If file is missing,   |
|                     | then stdout is flushed. If file is the null     |
|                     | string, then all open output files and pipes    |
|                     | have their buffers flushed.                     |
'---------------------+-------------------------------------------------'
| print ... >> file   | Appends output to the file.                     |
'---------------------+-------------------------------------------------'
| print ... | command | Writes on a pipe.                               |
'---------------------+-------------------------------------------------'
| print ... |&        | Sends data to a co-process.                     |
|   command           |                                                 |
'---------------------'-------------------------------------------------'


 =========================== Numeric Functions =========================

.---------------------.-------------------------------------------------.
|                     |                                                 |
| Function            | Description                                     |
|                     |                                                 |
'---------------------+-------------------------------------------------'
| atan2(y, x)         | Returns the arctangent of y/x in radians.       |
'---------------------+-------------------------------------------------'
| cos(expr)           | Returns the cosine of expr, which is in radians.|
'---------------------+-------------------------------------------------'
| exp(expr)           | The exponential function.                       |
'---------------------+-------------------------------------------------'
| int(expr)           | Truncates to integer.                           |
'---------------------+-------------------------------------------------'
| log(expr)           | The natural logarithm function.                 |
'---------------------+-------------------------------------------------'
| rand()              | Returns a random number N, between 0 and 1,     |
|                     | such that 0 <= N < 1.                           |
'---------------------+-------------------------------------------------'
| sin(expr)           | Returns the sine of expr, which is in radians.  |
'---------------------+-------------------------------------------------'
| sqrt(expr)          | The square root function.                       |
'---------------------+-------------------------------------------------'
| srand([expr])       | Uses expr as a new seed for the random number   |
|                     | generator. If no expr is provided, the time of  |
|                     | day is used. The return value is the previous   |
|                     | seed for the random number generator.           |
'---------------------'-------------------------------------------------'


 ====================== Bit Manipulation Functions =====================

.---------------------.-------------------------------------------------.
|                     |                                                 |
| Function            | Description                                     |
|                     |                                                 |
'---------------------+-------------------------------------------------'
| and(v1, v2)         | Return the bitwise AND of the values provided   |
|                     | by v1 and v2.                                   |
'---------------------+-------------------------------------------------'
| compl(val)          | Return the bitwise complement of val.           |
'---------------------+-------------------------------------------------'
| lshift(val, count)  | Return the value of val, shifted left by        |
|                     | count bits.                                     |
'---------------------+-------------------------------------------------'
| or(v1, v2)          | Return the bitwise OR of the values provided by |
|                     | v1 and v2.                                      |
'---------------------+-------------------------------------------------'
| rshift(val, count)  | Return the value of val, shifted right by       |
|                     | count bits.                                     |
'---------------------+-------------------------------------------------'
| xor(v1, v2)         | Return the bitwise XOR of the values provided   |
|                     | by v1 and v2.                                   |
'---------------------'-------------------------------------------------'


 =========================== String Functions ==========================

.---------------------.-------------------------------------------------.
|                     |                                                 |
| Function            | Description                                     |
|                     |                                                 |
'---------------------+-------------------------------------------------'
| asort(s [, d])      | Returns the number of elements in the source    |
|                     | array s.  The contents of s are sorted using    |
|                     | gawk's normal rules for comparing values, and   |
|                     | the indexes of the sorted values of s are       |
|                     | replaced with sequential integers starting with |
|                     | 1. If the optional destination array d is       |
|                     | specified, then s is first duplicated into d,   |
|                     | and then d is sorted, leaving the indexes of    |
|                     | the source array s unchanged.                   |
'---------------------+-------------------------------------------------'
| asorti(s [, d])     | Returns the number of elements in the source    |
|                     | array s. The behavior is the same as that of    |
|                     | asort(),  except that the array indices are     |
|                     | used for sorting, not the array values. When    |
|                     | done, the array is indexed numerically, and the |
|                     | values are those of the original indices. The   |
|                     | original values are lost; thus provide a second |
|                     | array if you wish to preserve the original.     |
'---------------------+-------------------------------------------------'
| gensub(r, s,        | Search the target string t for matches of the   |
|   h [, t])          | regular expression r.  If h is a string         |
|                     | beginning with g or G, then replace all matches |
|                     | of r with s. Otherwise, h is a number           |
|                     | indicating which match of r to replace. If t is |
|                     | not supplied, $0 is used instead. Within the    |
|                     | replacement text s, the sequence \n, where n is |
|                     | a digit from 1 to 9, may be used to indicate    |
|                     | just the text that matched the n'th             |
|                     | parenthesized subexpression. The sequence \0    |
|                     | represents the entire matched text, as does the |
|                     | character &. Unlike sub() and gsub(), the       |
|                     | modified string is returned as the result of    |
|                     | the function, and the original target string    |
|                     | is not changed.                                 |
'---------------------+-------------------------------------------------'
| gsub(r, s [, t])    | For each substring matching the regular         |
|                     | expression r in the string t, substitute the    |
|                     | string s, and return the number of              |
|                     | substitutions.  If t is not supplied, use $0.   |
|                     | An & in the replacement text is replaced with   |
|                     | the text that was actually matched. Use \& to   |
|                     | get a literal &.  (This must be                 |
|                     | typed as  "\\&")                                |
'---------------------+-------------------------------------------------'
| index(s, t)         | Returns the index of the string t in the        |
|                     | string s, or 0 if t is not present. (This       |
|                     | implies that characterindices start at one.)    |
'---------------------+-------------------------------------------------'
| length([s])         | Returns the length of the string s, or the      |
|                     | length of $0 if s is not supplied.              |
'---------------------+-------------------------------------------------'
| match(s, r [, a])   | Returns the position in s where the regular     |
|                     | expression r occurs, or 0 if r is not present,  |
|                     | and sets the values of RSTART and RLENGTH.      |
|                     | Note that the argument order is the same as for |
|                     | the ~ operator:  str  ~  re. If array a is      |
|                     | provided, a is cleared and then elements 1      |
|                     | through n are filled with the portions of s     |
|                     | that match the corresponding parenthesized      |
|                     | subexpression in r.  The 0'th element of a      |
|                     | contains the portion of s matched by the entire |
|                     | regular expression r. Subscripts a[n, "start"], |
|                     | and a[n, "length"] provide the starting index   |
|                     | in the string and length respectively, of each  |
|                     | matching substring.                             |
'---------------------+-------------------------------------------------'
| split(s, a [, r])   | Splits the string s into the array a on the     |
|                     | regular expression r, and returns the number of |
|                     | fields. If r is omitted, FS is used instead.    |
|                     | The array a is cleared first. Splitting behaves |
|                     | identically to field splitting.                 |
'---------------------+-------------------------------------------------'
| sprintf(fmt,        | Prints expr-list according to fmt, and returns  |
|   expr-list)        | the resulting string.                           |
'---------------------+-------------------------------------------------'
| strtonum(str)       | Examines str, and returns its numeric value.    |
|                     | If str begins with a leading 0, strtonum()      |
|                     | assumes that  str is an octal number. If str    |
|                     | begins with a leading 0x or 0X, strtonum()      |
|                     | assumes that str is a hexadecimal number.       |
'---------------------+-------------------------------------------------'
| sub(r, s [, t])     | Just like gsub(), but only the first matching   |
|                     | substring is replaced.                          |
'---------------------+-------------------------------------------------'
| substr(s, i [, n])  | Returns the at most n-character substring of s  |
|                     | starting at i.  If n is omitted, the rest of s  |
|                     | is used.                                        |
'---------------------+-------------------------------------------------'
| tolower(str)        | Returns a copy of the string str, with all the  |
|                     | upper-case characters in str translated to      |
|                     | their corresponding lower-case counterparts.    |
|                     | Non-alphabetic characters are left unchanged.   |
'---------------------+-------------------------------------------------'
| toupper(str)        | Returns a copy of the string str, with all the  |
|                     | lower-case characters in str translated to      |
|                     | their corresponding upper-case counterparts.    |
|                     | Non-alphabetic characters are left unchanged.   |
'---------------------'-------------------------------------------------'


 ============================ Time Functions ===========================

.---------------------.-------------------------------------------------.
|                     |                                                 |
| Function            | Description                                     |
|                     |                                                 |
'---------------------+-------------------------------------------------'
| mktime(datespec)    | Turns datespec into a time stamp of the same    |
|                     | form as returned by systime(). The datespec is  |
|                     | a string of the form YYYY MM DD HH MM SS[ DST]. |
|                     | The contents of the string are six or seven     |
|                     | numbers representing respectively the full year |
|                     | including century, the month from 1 to 12, the  |
|                     | day of the month from 1 to 31, the hour of the  |
|                     | day from 0 to 23, the minute from 0 to 59, and  |
|                     | the second from 0 to 60, and an optional        |
|                     | daylight saving flag. The values of these       |
|                     | numbers need not be within the ranges           |
|                     | specified; for example, an hour of -1 means 1   |
|                     | hour before midnight. The origin-zero Gregorian |
|                     | calendar is assumed, with year 0 preceding year |
|                     | 1 and year -1 preceding year 0. The time is     |
|                     | assumed to be in the local timezone. If the     |
|                     | daylight saving flag is positive, the time is   |
|                     | assumed to be daylight saving time; if zero,    |
|                     | the time is assumed to be standard time; and if |
|                     | negative (the default), mktime() attempts to    |
|                     | determine whether daylight saving time is in    |
|                     | effect for the specified time. If datespec does |
|                     | not contain enough elements or if the resulting |
|                     | time is out of range, mktime() returns -1.      |
'---------------------+-------------------------------------------------'
| strftime([format    | Formats timestamp according to the              |
|   [, timestamp]])   | specification in format. The timestamp should   |
|                     | be of the same form as returned by systime().   |
|                     | If timestamp is missing, the current time of    |
|                     | day is used.If format is missing, a default     |
|                     | format equivalent to the output of date(1) is   |
|                     | used.  See the specification for the strftime() |
|                     | function in ANSI C for the format conversions   |
|                     | that are guaranteed to be available. A          |
|                     | public-domain version of strftime(3) and a man  |
|                     | page for it come with gawk; if that version was |
|                     | used to build gawk, then all of the conversions |
|                     | described in that man page are available to     |
|                     | gawk.                                           |
'---------------------+-------------------------------------------------'
| systime()           | Returns the current time of day as the number   |
|                     | of seconds since the Epoch (1970-01-01 00:00:00 |
|                     | UTC on POSIX systems).                          |
'---------------------'-------------------------------------------------'


 =============== Internationalization (I18N)  Functions ================

.---------------------.-------------------------------------------------.
|                     |                                                 |
| Function            |                                                 |
|                     |                                                 |
| Description         |                                                 |
|                     |                                                 |
'---------------------+-------------------------------------------------'
| bindtextdomain(directory [, domain])                                  |
|                                                                       |
| Specifies the directory where gawk looks for the .mo files. It        |
| returns the directory where domain is ``bound.'' The default domain   |
| is the value of TEXTDOMAIN.  If directory is the null string (""),    |
| then bindtextdomain() returns the current binding for the given domain|
'---------------------+-------------------------------------------------'
| dcgettext(string [, domain [, category]])                             |
|                                                                       |
| Returns the translation of string in text domain domain for locale    |
| category category. The default value for domain is the current value  |
| of TEXTDOMAIN. The default value for category is "LC_MESSAGES". If    |
| you supply a value for category, it must be a string equal to one of  |
| the known locale categories. You must also supply a text domain. Use  |
| TEXTDOMAIN if you want to use the current domain.                     |
'---------------------+-------------------------------------------------'
| dcngettext(string1 , string2 , number [, domain [, category]])        |
|                                                                       |
| Returns the plural form used for number of the translation of string1 |
| and string2 in text domain domain for locale category category. The   |
| default value for domain is the current value of TEXTDOMAIN. The      |
| default value for category is "LC_MESSAGES". If you supply a value    |
| for category, it must be a string equal to one of the known locale    |
| categories. You must also supply a text domain. Use TEXTDOMAIN if     |
| you want to use the current domain.                                   |
'---------------------'-------------------------------------------------'




 =============== GNU AWK's Command Line Argument Summary ===============

.-------------------------.---------------------------------------------.
|                         |                                             |
| Argument                | Description                                 |
|                         |                                             |
'-------------------------+---------------------------------------------'
| -F fs                   | Use fs for the input field separator        |
| --field-sepearator fs   | (the value of the FS predefined variable).  |
'-------------------------+---------------------------------------------'
| -v var=val              | Assign the value val to the variable var,   |
| --assign var=val        | before execution of the program begins.     |
|                         | Such variable values are available to the   |
|                         | BEGIN block of an AWK program.              |
'-------------------------+---------------------------------------------'
| -f program-file         | Read the AWK program source from the file   |
| --file program-file     | program-file, instead of from the first     |
|                         | command line argument. Multiple -f          |
|                         | (or --file) options may be used.            |
'-------------------------+---------------------------------------------'
| -mf NNN                 | Set various memory limits to the value NNN. |
| -mr NNN                 | The f flag sets the maximum number of       |
|                         | fields, and the r flag sets the maximum     |
|                         | record size. (Ignored by gawk, since gawk   |
|                         | has no pre-defined limits)                  |
'-------------------------+---------------------------------------------'
| -W compat               | Run in compatibility mode. In compatibility |
| -W traditional          | mode, gawk behaves identically to UNIX awk; |
| --compat--traditional   | none of the GNU-specific extensions are     |
|                         | recognized.                                 |
'-------------------------+---------------------------------------------'
| -W copyleft             | Print the short version of the GNU copyright|
| -W copyright            | information message on the standard output  |
| --copyleft              | and exit successfully.                      |
| --copyright             |                                             |
'-------------------------+---------------------------------------------'
| -W dump-variables[=file]| Print a sorted list of global variables,    |
| --dump-variables[=file] | their types and final values to file. If no |
|                         | file is provided, gawk uses a file named    |
|                         | awkvars.out in the current directory.       |
'-------------------------+---------------------------------------------'
| -W help                 | Print a relatively short summary of the     |
| -W usage                | available options on the standard output.   |
| --help                  |                                             |
| --usage                 |                                             |
'-------------------------+---------------------------------------------'
|-W lint[=value]          | Provide warnings about constructs that      |
|--lint[=value]           | are dubious or non-portable to other AWK    |
|                         | impl’s. With argument fatal, lint warnings  |
|                         | become fatal errors. With an optional       |
|                         | argument of invalid, only warnings about    |
|                         | things that are actually invalid are        |
|                         | issued. (This is not fully implemented yet.)|
'-------------------------+---------------------------------------------'
| -W lint-old--lint-old   | Provide warnings about constructs that are  |
|                         | not portable to the original version of     |
|                         | Unix awk.                                   |
'-------------------------+---------------------------------------------'
| -W gen-po--gen-po       | Scan and parse the AWK program, and         |
|                         | generate a GNU .po format file on standard  |
|                         | output with entries for all localizable     |
|                         | strings in the program. The program itself  |
|                         | is not executed.                            |
'-------------------------+---------------------------------------------'
| -W non-decimal-data     | Recognize octal and hexadecimal values in   |
| --non-decimal-data      | input data.                                 |
'-------------------------+---------------------------------------------'
| -W posix--posix         | This turns on compatibility mode, with the  |
|                         | following additional restrictions:          |
|                         | o  \x escape sequences are not recognized.  |
|                         | o  Only space and tab act as field          |
|                         |    separators when FS is set to a single    |
|                         |    space, new-line does not.                |
|                         | o  You cannot continue lines after ? and :. |
|                         | o  The synonym func for the keyword function|
|                         |    is not recognized.                       |
|                         | o  The operators ** and **= cannot be used  |
|                         |    in place of ^ and ^=.·  The fflush()     |
|                         |    function is not available.               |
'-------------------------+---------------------------------------------'
| -W profile[=prof_file]  | Send profiling data to prof_file.           |
| --profile[=prof_file]   | The default is awkprof.out. When run with   |
|                         | gawk, the profile is just a "pretty         |
|                         | printed" version of the program. When run   |
|                         | with pgawk, the profile contains execution  |
|                         | counts of each statement in the program     |
|                         | in the left margin and function call counts |
|                         | for each user-defined function.             |
'-------------------------+---------------------------------------------'
| -W re-interval          | Enable the use of interval expressions in   |
| --re-interval           | regular expression matching. Interval       |
|                         | expressions were not traditionally          |
|                         | available in the AWK language.              |
'-------------------------+---------------------------------------------'
| -W source program-text  | Use program-text as AWK program source      |
| --source program-text   | code. This option allows the easy           |
|                         | intermixing of library functions (used via  |
|                         | the -f and --file options) with source code |
|                         | entered on the command line.                |
'-------------------------+---------------------------------------------'
| -W version              | Print version information for this          |
| --version               | particular copy of gawk on the standard     |
|                         | output.                                     |
'-------------------------+---------------------------------------------'
| --                      | Signal the end of options. This is useful   |
|                         | to allow further arguments to the AWK       |
|                         | program itself to start with a "-". This    |
|                         | is mainly for consistency with the argument |
|                         | parsing convention used by most other POSIX |
|                         | programs.                                   |
'-------------------------'---------------------------------------------'

 =======================================================================

.-----------------------------------------------------------------------.
| Peteris Krumins (peter@catonmat.net), 2007.08.22                      |
| http://www.catonmat.net  -  good coders code, great reuse             |
'-----------------------------------------------------------------------'