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Re: Stripping spaces from a shell variable, portably


DervishD wrote [2003/10/01]:
>     Hi all :))
>     I need to strip leading and trailing spaces from the contents of
> a shell variable, and I need to do it portably, with a construct like
> ${...%% } and with no loops. When I say 'portably' I mean using SuSv3
> constructs, not Zsh extensions.
>     I've tried the obvious ${variable# } for stripping a single
> space, but this needs a while loop, which I want to avoid (although
> it seems to be portable):
>     while [ "$variable" != "${variable# }" ]
>     do
>         variable="${variable# }"
>     done
>     And the same with the '%' construct. Please note that I cannot
> use '[[' for the test, since it must be portable, and this involves
> exec'ing the 'test' binary for each space in the variable :((
>     If no solution is possible I'll use 'tr', because the shell code
> must run in bash and zsh at least, but I really want it to be able to
> run in any SuSv3 compliant shell.

Why not
  variable=`echo "$variable" | sed -e 's/^ *//' -e 's/ *$//'`

I'm not sure whether all versions of sed understand multiple
"-e" arguments, so it might me necessary to use this:
  variable=`echo "$variable" | sed -e 's/^ *//' | sed -e 's/ *$//'`

>     Thanks a lot for your help :)
>     Raúl Núñez de Arenas Coronado


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