Multiple variable assignments from command output in BASH

read day month year <<< $(date +'%d %m %y')

This version uses read instead of eval.

By: putnamhill

2011-07-29 15:05:19

date read bash read

2 Alternatives + Submit Alt

Multiple variable assignments from command output in BASH

No command substitution but subshell redirection
This is sample output - yours may be different.
10

read day month year < <(date +'%d %m %y')

frans · 2011-07-30 06:06:29 3
Multiple variable assignments from command output in BASH

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". Show Sample Output
This is sample output - yours may be different.
```
$ eval $(date +"day=%d; month=%m; year=%y")
$ echo $day/$month/$year
29/07/11
```
4

eval $(date +"day=%d; month=%m; year=%y")

xakon · 2011-07-29 12:47:26 10

What Others Think

Mozai · 619 weeks ago

Meant to say: I adore the '

Mozai · 619 weeks ago

Third attempt: I adore the '<<<' operator in bash.

Mozai · 619 weeks ago

If your input contains spaces and newlines, use: read -d "\n"

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