Bash One-Liners Explained, Part I: Working with files

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June 08, 2012, 10:48

Great post, you covered awesome stuff, and unlike most bash tips, you actually understand bash and all the gotchas it has.

One quick note on #4, where you cat the file and | into while read line, be careful with this approach. The while loop is now created in a subshell, so any variables modified within the context of the while loop will not persist when the loop exits.

ex. (let's say foo.txt has 10 lines)

i=0
cat foo.txt | while read line; do ((i++)); done
echo "$i"

will print 0.

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