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AWK is a small but powerful programming language that can process and convert text files. AWK is part of every Unix-derived system.
Each AWK program consists of pattern-action statements.
The program reads each input line, checks lines against patterns, and runs matching actions.
For programs that never read input lines, the entire program can be one BEGIN { ... } block.
- ''List users who have /bin/ksh as a shell.''
$ awk -F: '$7 == "/bin/ksh" { print $1 }' /etc/passwd
AWK has only three types of variables: they are strings, floating-point numbers, and associative arrays (where every array index is a string). Conversion between strings and numbers is automatic. AWK also has regular expressions, which appear in many AWK programs. There are a few built-in functions, like cos() and sprintf().
- ''Find average line length.''
$ awk '{ cnt += length($0) } END { print cnt / NR }' /etc/rc
The name "AWK" comes from the initials of Alfred Aho, Peter Weinberger and Brian Kernighan: they invented AWK during the 1970s. A few decades later, Kernighan continues to maintain the reference implementation of AWK.
Links
*[http://leaf.dragonflybsd.org/cgi/web-man?command=awk§ion=1 awk(1) manual page], short and brief *[https://www.gnu.org/software/gawk/ gawk] GNU awk [https://www.gnu.org/software/gawk/manual/ manual] *AWK in Wikipedia *[http://awk.info AWK Community Portal]
Online-Execution
- [http://ideone.com ideone.com] - gawk, mawk (both are kept up to date)