Built-in Variables that Control awk

This is an alphabetical list of the variables which you can change to control how awk does certain things. Those variables that are specific to gawk are marked with an asterisk, `*'.

CONVFMT

This string controls conversion of numbers to strings (see section Conversion of Strings and Numbers). It works by being passed, in effect, as the first argument to the sprintf function (see section Built-in Functions for String Manipulation). Its default value is "%.6g". CONVFMT was introduced by the POSIX standard.

FIELDWIDTHS *

This is a space separated list of columns that tells gawk how to split input with fixed, columnar boundaries. It is an experimental feature. Assigning to FIELDWIDTHS overrides the use of FS for field splitting. See section Reading Fixed-width Data, for more information. If gawk is in compatibility mode (see section Command Line Options), then FIELDWIDTHS has no special meaning, and field splitting operations are done based exclusively on the value of FS.

FS

FS is the input field separator (see section Specifying How Fields are Separated). The value is a single-character string or a multi-character regular expression that matches the separations between fields in an input record. If the value is the null string (""), then each character in the record becomes a separate field. The default value is " ", a string consisting of a single space. As a special exception, this value means that any sequence of spaces, tabs, and/or newlines is a single separator.(8) It also causes spaces, tabs, and newlines at the beginning and end of a record to be ignored. You can set the value of FS on the command line using the `-F' option:

awk -F, 'program' input-files

If gawk is using FIELDWIDTHS for field-splitting, assigning a value to FS will cause gawk to return to the normal, FS-based, field splitting. An easy way to do this is to simply say `FS = FS', perhaps with an explanatory comment.

IGNORECASE *

If IGNORECASE is non-zero or non-null, then all string comparisons, and all regular expression matching are case-independent. Thus, regexp matching with `~' and `!~', and the gensub, gsub, index, match, split and sub functions, record termination with RS, and field splitting with FS all ignore case when doing their particular regexp operations. The value of IGNORECASE does not affect array subscripting. See section Case-sensitivity in Matching. If gawk is in compatibility mode (see section Command Line Options), then IGNORECASE has no special meaning, and string and regexp operations are always case-sensitive.

OFMT

This string controls conversion of numbers to strings (see section Conversion of Strings and Numbers) for printing with the print statement. It works by being passed, in effect, as the first argument to the sprintf function (see section Built-in Functions for String Manipulation). Its default value is "%.6g". Earlier versions of awk also used OFMT to specify the format for converting numbers to strings in general expressions; this is now done by CONVFMT.

OFS

This is the output field separator (see section Output Separators). It is output between the fields output by a print statement. Its default value is " ", a string consisting of a single space.

ORS

This is the output record separator. It is output at the end of every print statement. Its default value is "\n". (See section Output Separators.)

RS

This is awk's input record separator. Its default value is a string containing a single newline character, which means that an input record consists of a single line of text. It can also be the null string, in which case records are separated by runs of blank lines, or a regexp, in which case records are separated by matches of the regexp in the input text. (See section How Input is Split into Records.)

SUBSEP

SUBSEP is the subscript separator. It has the default value of "\034", and is used to separate the parts of the indices of a multi-dimensional array. Thus, the expression foo["A", "B"] really accesses foo["A\034B"] (see section Multi-dimensional Arrays).

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