Writing a simple bash filter

Udgivet den august 3, 2018 af Slet mig

To write a simple bash filter application, start by declaring
your filter as a bash script with #!/usr/bin/env bash.
This informs your shell what interpreter to use when running the script.

The trick to writing a filter is to read lines from a filename if supplied
${1},
or from /dev/stdin
if no filename is supplied.

An example script lowercase

#!/usr/bin/env bash

while read line; do
    echo ${line,,}
done < "${1:-/dev/stdin}"

This script can then be utilized in a pipeline, e.g. cat file | lowercase
or by feeding it a filename,

lowercase file.

 

Dette indlæg blev udgivet i Programmering, Shellscript. Bogmærk permalinket.

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