diff options
Diffstat (limited to 'gawk.1')
| -rw-r--r-- | gawk.1 | 280 |
1 files changed, 218 insertions, 62 deletions
@@ -9,9 +9,9 @@ gawk \- pattern scanning and processing language ] [ .B \-D ] [ -.B \-i -] [ .B \-v +] [ +.B \-V ] .. [ @@ -33,9 +33,9 @@ gawk \- pattern scanning and processing language ] [ .B \-D ] [ -.B \-i -] [ .B \-v +] [ +.B \-V ] .. [ @@ -76,13 +76,7 @@ Use for the input field separator (the value of the .B FS predefined -variable). For compatibility with \s-1UNIX\s+1 -.IR awk , -if -.I fs -is ``t'', then -.B FS -will be set to the tab character. +variable). .TP .BI \-f " program-file" Read the AWK program source from the file @@ -130,6 +124,17 @@ type your program, and end it with a .B ^D (control-d). .PP +The environment variable +.B AWKPATH +specifies a search path to use when finding source files named with +the +.B \-f +option. If this variable does not exist, the default path is +\fB".:/usr/lib/awk:/usr/local/lib/awk"\fR. +If a file name given to the +.B \-f +option contains a ``/'' character, no path search is performed. +.PP .I Gawk compiles the program into an internal form, and then proceeds to read @@ -184,6 +189,11 @@ In the special case that .B FS is a single blank, fields are separated by runs of blanks and/or tabs. +Note that the value of +.B IGNORECASE +(see below) will also affect how fields are split when +.B FS +is a regular expression. .PP Each field in the input line may be referenced by its position, .BR $1 , @@ -223,12 +233,12 @@ to be recomputed, with the fields being separated by the value of AWK's built-in variables are: .PP .RS -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B ARGC the number of command line arguments (does not include options to .IR gawk , or the program source). -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B ARGV array of command line arguments. The array is indexed from 0 to @@ -237,7 +247,7 @@ array of command line arguments. The array is indexed from Dynamically changing the contents of .B ARGV can control the files used for data. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B ENVIRON An array containing the values of the current environment. The array is indexed by the environment variables, each element being @@ -248,36 +258,64 @@ Changing this array does not affect the environment seen by programs which spawns via redirection or the .B system function. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B FILENAME the name of the current input file. If no files are specified on the command line, the value of .B FILENAME is ``\-''. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B FNR the input record number in the current input file. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B FS the input field separator, a blank by default. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' +.B IGNORECASE +Controls the case-sensitivity of all regular expression operations. If +.B IGNORECASE +has a non-zero value, then pattern matching in rules, +field splitting with +.BR FS , +regular expression +matching with +.B ~ +and +.BR !~ , +and the +.BR gsub() , +.BR match() , +.BR split() , +and +.B sub() +pre-defined functions will all ignore case when doing regular expression +operations. Thus, if +.B IGNORECASE +is not equal to zero, +.B /aB/ +matches all of the strings \fB"ab"\fP, \fB"aB"\fP, \fB"Ab"\fP, +and \fB"AB"\fP. +As with all AWK variables, the initial value of +.B IGNORECASE +is zero, so all regular expression operations are normally case-sensitive. +.TP \l'\fBIGNORECASE\fR' .B NF the number of fields in the current input record. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B NR the total number of input records seen so far. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B OFMT the output format for numbers, .B %.6g by default. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B OFS the output field separator, a blank by default. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B ORS the output record separator, by default a newline. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B RS the input record separator, by default a newline. .B RS @@ -292,17 +330,17 @@ is set to the null string, then the newline character always acts as a field separator, in addition to whatever value .B FS may have. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B RSTART the index of the first character matched by .BR match() ; 0 if no match. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B RLENGTH the length of the string matched by .BR match() ; \-1 if no match. -.TP \l'\fBFILENAME\fR' +.TP \l'\fBIGNORECASE\fR' .B SUBSEP the character used to separate multiple subscripts in array elements, by default \fB"\e034"\fR. @@ -740,6 +778,11 @@ functions accept the following conversion specification formats: .TP .B %c An ASCII character. +If the argument used for +.B %c +is numeric, it is treated as a character and printed. +Otherwise, the argument is assumed to be a string, and the only first +character of that string is printed. .TP .B %d A decimal number (the integer part). @@ -803,6 +846,53 @@ However, they may be simulated by using the AWK concatenation operation to build up a format specification dynamically. .PP +When doing I/O redirection from either +.B print +or +.B printf +into a file, +or via +.B getline +from a file, +.I gawk +recognizes certain special filenames internally. These filenames +allow access to open file descriptors inherited from +.IR gawk 's +parent process (usually the shell). The filenames are: +.RS +.TP +.B /dev/stdin +The standard input. +.TP +.B /dev/stdout +The standard output. +.TP +.B /dev/stderr +The standard error output. +.TP +.BI /dev/fd/\^ n +The file denoted by the open file descriptor +.IR n . +.RE +.PP +These are particularly useful for error messages. For example: +.PP +.RS +.ft B +print "You blew it!" > "/dev/stderr" +.ft R +.RE +.PP +whereas you would otherwise have to use +.PP +.RS +.ft B +print "You blew it!" | "cat 1>&2" +.ft R +.RE +.PP +These file names may also be used on the command line to name data files. +.PP AWK has the following pre-defined arithmetic functions: .PP .RS @@ -922,6 +1012,22 @@ If is omitted, the rest of .I s is used. +.TP \l'\fBsprintf(\fIfmt\fB, \fIexpr-list\fB)\fR' +.BI tolower( str ) +returns a copy of the string +.IR str , +with all the upper-case characters in +.I str +translated to their corresponding lower-case counterparts. +Non-alphabetic characters are left unchanged. +.TP \l'\fBsprintf(\fIfmt\fB, \fIexpr-list\fB)\fR' +.BI toupper( str ) +returns a copy of the string +.IR str , +with all the lower-case characters in +.I str +translated to their corresponding upper-case counterparts. +Non-alphabetic characters are left unchanged. .RE .PP String constants in AWK are sequences of characters enclosed @@ -931,6 +1037,9 @@ are recognized, as in C. These are: .PP .RS .TP \l'\fB\e\fIddd\fR' +.B \ea +The ``alert'' character; usually the ASCII BEL character. +.TP \l'\fB\e\fIddd\fR' .B \eb backspace. .TP \l'\fB\e\fIddd\fR' @@ -949,10 +1058,24 @@ horizontal tab. .B \ev vertical tab. .TP \l'\fB\e\fIddd\fR' +.BI \ex "\^hex digits" +The character represented by the string of hexadecimal digits following +the +.BR \ex . +As in ANSI C, all following hexadecimal digits are considered part of +the escape sequence. +(This feature should tell us something about language design by committee.) +E.g., "\ex1B" is the ASCII ESC (escape) character. +.TP \l'\fB\e\fIddd\fR' .BI \e ddd The character represented by the 1-, 2-, or 3-digit sequence of octal digits. E.g. "\e033" is the ASCII ESC (escape) character. .RE +.PP +The escape sequences may also be used inside constant regular expressions +(e.g., +.B "/[\ \et\ef\en\er\ev]/" +matches whitespace characters). .SH FUNCTIONS Functions in AWK are defined as follows: .PP @@ -1064,10 +1187,8 @@ array. .I Gawk has some extensions to System V .IR awk . -They are described in this section. -All features described in this section may change at some time in -the future, or may go away entirely. They can be disabled either by -compiling +They are described in this section. All the extensions described here +can be disabled by compiling .I gawk with .BR \-DSTRICT , @@ -1075,25 +1196,51 @@ or by invoking .I gawk with the name .IR awk . -You should not write programs that depend upon them. -.PP -The environment variable -.B AWKPATH -specifies a search path to use when finding source files named with -the -.B \-f -option. If this variable does not exist, the default path is -\fB".:/usr/lib/awk:/usr/local/lib/awk"\fR. -If a file name given to the -.B \-f -option contains a ``/'' character, no path search is performed. +If the underlying operating system supports the +.B /dev/fd +directory and corresponding files, then +.I gawk +can be compiled with +.B \-DNO_DEV_FD +to disable the special filename processing. .PP -Two new relational operators are defined, -.BR ~~ , +The following features of +.I gawk +are not available in +System V +.IR awk . +.RS +.TP \l'\(bu' +\(bu +The +.BR \ea , +.BR \ev , +or +.B \ex +escape sequences are not recognized. +.TP \l'\(bu' +\(bu +The special file names available for I/O redirection are not recognized. +.TP \l'\(bu' +\(bu +The +.B tolower and -.BR !~~ . -These perform case independent regular expression match and no-match -operations, respectively. +.B toupper +built-in string functions are not available. +.TP \l'\(bu' +\(bu +The +.B IGNORECASE +variable and its side-effects are not available. +.TP \l'\(bu' +\(bu +No path search is performed for files named via the +.B \-f +option. Therefore the +.B AWKPATH +environment variable is not special. +.RE .PP The AWK book does not define the return value of the .B close @@ -1106,8 +1253,25 @@ or .IR pclose (3), when closing a file or pipe, respectively. .PP +When +.I gawk +is invoked as +.IR awk , +if the +.I fs +argument to the +.B \-F +option is ``t'', then +.B FS +will be set to the tab character. +Since this is a rather ugly special case, it is not the default behavior. +.PP +The rest of the features described in this section may change at some time in +the future, or may go away entirely. +You should not write programs that depend upon them. +.PP .I Gawk -accepts the following additional arguments: +accepts the following additional options: .ig .TP .B \-D @@ -1131,18 +1295,6 @@ maintainers, and may not even be compiled into .IR gawk . .. .TP -.B \-i -Ignore case when doing regular expression operations. -This causes -.B ~ -and -.B !~ -to behave like the new operators -.B ~~ -and -.BR !~~ , -described above. -.TP .B \-v Print version information for this particular copy of .I gawk @@ -1152,6 +1304,9 @@ This is useful mainly for knowing if the current copy of on your system is up to date with respect to whatever the Free Software Foundation is distributing. +.TP +.B \-V +Print the GNU copyright information message on the error output. .SH BUGS The .B \-F @@ -1164,12 +1319,13 @@ was designed and implemented by Alfred Aho, Peter Weinberger, and Brian Kernighan of AT&T Bell Labs. Brian Kernighan continues to maintain and enhance it. .PP -Paul Rubin and Jay Fenlason, with John Woods, -all of the Free Software Foundation, wrote +Paul Rubin and Jay Fenlason, +of the Free Software Foundation, wrote .IR gawk , to be compatible with the original version of .I awk distributed in Seventh Edition \s-1UNIX\s+1. +John Woods contributed a number of bug fixes. David Trueman of Dalhousie University, with contributions from Arnold Robbins at Emory University, made .I gawk |