Differences

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--- bash-stdin-or-filename [2024/02/01 23:30] – dblume
+++ bash-stdin-or-filename [2024/02/19 14:31] (current) – Moving because now have stdin and stdout sections dblume
@@ Line 1: / Line 1: @@
-====== Bash Script Stdin or Filename ======
-If you write a shell script and want it to run with either stdin or a filename, like so:
-    cat file.txt | script.sh
-    script.sh file.txt
-There are some options. Here we'll use ''awk'' as the command inside the script.
-=== The General, Idiomatic Way ===
-The canonical way is to cat the args to the script.
-<file bash script.sh>
-#!/usr/bin/env sh
-cat "$@" | awk -F, '...'
-</file>
-=== Shell Default Parameter Substitution ===
-Use Bash parameter substitution to try to pass in ''$1'', but if it doesn't exist, pass in ''/dev/stdin''.
-<file bash script.sh>
-#!/usr/bin/env sh
-awk -F, '...' "${1:-/dev/stdin}"
-</file>
-=== Let the Command Handle It ===
-Since we're using ''awk'' as our example, and it already supports stdin or filenames, don't be a
-bash script, be an awk script. (But in this case we can't use ''/usr/bin/env''.)
-<file bash script.awk>
-#!/bin/awk -f
-BEGIN{FS=","} ...
-</file>