Writing AWK scripts
Many large AWK scripts are wrapped in a useless shell script. If all of your logic is in AWK then there’s no need for the shell to get involves in things; just use the correct shebang!
#!/usr/bin/awk -f
BEGIN { print("start") }
END { print("end") }Just make it executable and now you have a
script written directly in AWK with no
shells involved. Just make it executable
(with chmod +x as usual) and you are
good to go.
Why bother? It makes the script simpler
(e.g. no multiple levels of quoting and
escaping), makes it slightly less resource
intensive to start (only a single fork and
exec) and run (no shell waiting around for
the awk interpreter to finish), and makes
the script sightly easier to handle with
tools like syntax highlighting, code
formatting, etc.
Code formatting
Like any body of code, the formatting of a longer AWK script can be an important help or hindrance to anyone trying to understand it. GNU AWK has a helpful option to format AWK scripts.
#!/usr/bin/awk -f
BEGIN { print("start"); }
END { print("end") }We can format this AWK script like so:
$ gawk -f example.awk -o-
#!/usr/bin/awk -f
BEGIN {
print("start")
}
END {
print("end")
}We use -f to read the AWK script from a
file and -o to format and output the
script.
In this case, we’re writing it to the
standard output (-o-) but we could also
write it to another (different!) file with
-oformatted.awk) or use -o and let
awk write it to the default output file
(awkprof.out).