Conditionally command line export variable

Question

If I run

export COMMAND=nonexistentcommand && which $COMMAND >/dev/null || \
(echo "download filewithcommand.sh" && export COMMAND=./filewithcommand.sh)

echo "command: $COMMAND"

I get

download filewithcommand.sh
command: nonexistentcommand

But I think it should be

download filewithcommand.sh
command: ./filewithcommand.

What's wrong with this sentence?

For reference, see What are the shell's control and redirection operators? — specifically, section A.4 of the first answer. — G-Man Says 'Reinstate Monica', Feb 28 '16 at 19:45

score 3 · Answer 1 · answered Feb 28 '16 at 19:07

3

COMMAND is set to nonexistentcommand and that's the output that you get. Normal.

You do set COMMAND to some other value, but that's in a subshell (enclosed in parentheses) so it doesn't affect the environment of the parent shell. Did you mean to use { braces } (which don't fork a subshell) instead of ( parentheses )?

answered Feb 28 '16 at 19:07

Celada

44,132

Yeah. This is the good response. You are great ;). I just have had to add an ending semicolon at the end of the last command. – Manel R. Doménech Feb 28 '16 at 19:37

Conditionally command line export variable

1 Answers1