How to trim whitespace from a Bash variable?

string bash variables trim
too much php picture too much php · Dec 15, 2008 · Viewed 1.4M times · Source

I have a shell script with this code:

var=`hg st -R "$path"`
if [ -n "$var" ]; then
    echo $var
fi

But the conditional code always executes, because hg st always prints at least one newline character.

  • Is there a simple way to strip whitespace from $var (like trim() in PHP)?

or

  • Is there a standard way of dealing with this issue?

I could use sed or AWK, but I'd like to think there is a more elegant solution to this problem.

Answer

makevoid picture makevoid · Oct 19, 2012

A simple answer is:

echo "   lol  " | xargs

Xargs will do the trimming for you. It's one command/program, no parameters, returns the trimmed string, easy as that!

Note: this doesn't remove all internal spaces so "foo bar" stays the same; it does NOT become "foobar". However, multiple spaces will be condensed to single spaces, so "foo bar" will become "foo bar". In addition it doesn't remove end of lines characters.

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