awk

Column based editing

Get the nth column

echo 'one two three' | awk '{print $1}'

evaluates to:

one

Specify a delimier

The space (or multiple spaces/tabs) is the default delimiter. Specify a different delimiter:

echo 'one,two,three' | awk -F , '{print $1}'

Unbuffered output

Sometimes it is needed to flush the output to stdout.

In the following example, sed is used to remove the first character from the output of awk:

tail -f nginx.log | awk '{print $4 " " $9; fflush(stdout)}' | sed 's/.//'

Maintaining column alignment

Check out the split function in awk. Here is a good discussion: https://stackoverflow.com/a/20836890/1589512

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• Tag: shell