If I run the command
FOO=bar echo $FOO
I would expect it to bar, but it just echoes an empty string.
It appears that $FOO is not getting set.
What am I doing wrong?
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jonrsharpe
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PortMan
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2Did you read e.g. https://stackoverflow.com/q/10938483/3001761? – jonrsharpe Oct 17 '22 at 20:59
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1Environment variables in your shell commands are evaluated *before* the command executes. You need to ensure that the variable expansion happens in the child process. Try `FOO=bar sh -c 'echo $FOO'` and see if that produces different behavior. – larsks Oct 17 '22 at 21:00
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1Or with evil eval: `FOO=bar eval 'echo $FOO'` – Ted Lyngmo Oct 17 '22 at 21:02
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Or `FOO=bar; echo $FOO`, with the side-effect that `FOO` remains set – Diego Torres Milano Oct 17 '22 at 21:14
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This is [BashFAQ/104](https://mywiki.wooledge.org/BashFAQ/104) – M. Nejat Aydin Oct 17 '22 at 21:17
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The environment variable *is* set; `echo` just ignores its environment. The expansion of `$FOO` to produce the *argument* to `echo` is an entirely separate situation. – chepner Oct 17 '22 at 21:34