The awk report generator combines the regular expression features of grep and sed with the programming flexibility of the C language.

Its name derives from the initials of the authors of the original version, Alfred Aho, Peter Weinberger, and Brian Kernighan, all of Bell Labs.

Originally written in 1977, awk was updated in 1985 and released as nawk. Since then variations have been developed and released with different versions of Unix or its clones. On our system, awk, and nawk link back to the mawk program.

Although awk can be applied to any text data file, it is most useful processing data arranged in table format, i.e. rows and columns. awk treats each line of a file as a record and each word in the line as a field. The user may limit the scope of action applied to a record based on its record number, line contents, or even particular field contents. awk provides logical, arithmetic, and regular expressions filters to accomplish this.

General syntax :

awk [options] -f cmd_file data-file[s]

[options]

-F Field_separator : defines input filed separators. This is useful if the field or column separator is something other than white-space.

Default field seperator is white space. Multiple contiguous spaces are views as a single seperator.

But it is often useful to be able to select an alternative field separator. This can be specified on command line or wit a awk command.

-v var=value : initializes awk variables from the command line.
These are the basic standard options available for awk. See the awk man page Gnu specific options.

-f cmd-file : contains awk commands. Commands can be given on command line, but because awk also uses $ to dereference both fields and variables, using a file is easier.

list of one or more files containing the data to be processed. If you wish to preserve the output, use redirection. Note that the output will be a single stream of data even if several data files are processed.