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Multiple variable assignments from command output in BASH

Terminal - Multiple variable assignments from command output in BASH
read day month year < <(date +'%d %m %y')
2011-07-30 06:06:29
User: frans
Functions: date read
10
Multiple variable assignments from command output in BASH

No command substitution but subshell redirection

Alternatives

There are 8 alternatives - vote for the best!

Terminal - Alternatives
read day month year <<< $(date +'%d %m %y')
2011-07-29 15:05:19
User: putnamhill
Functions: date read
Tags: bash read
47

This version uses read instead of eval.

eval $(date +"day=%d; month=%m; year=%y")
2011-07-29 12:47:26
User: xakon
Functions: date eval
Tags: bash eval
4

It's quite easy to capture the output of a command and assign it in a shell's variable:

day=$(date +%d) month=$(date +%m)

But, what if we want to perform the same task with just one program invocation? Here comes the power of eval! date(1) outputs a string like "day=29; month=07; year=11" (notice the semicolons I added on purpose at date's custom output) which is a legal shell line. This like is then parsed and executed by the shell once again with the help of eval. Just setting 3 variables!

Inspired by LinuxJournal's column "Dave Taylor's Work the Shell".

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What others think

Very cute. I love it.

Comment by kaedenn 173 weeks and 5 days ago

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