Am 01.07.2010 00:22, schrieb Victor Lowther: > On Wed, 2010-06-30 at 23:56 +0200, Thomas Bächler wrote: >> Am 30.06.2010 23:47, schrieb Victor Lowther: >>> It is worth 10 - 30% speedup whenever you want to compare something. >> >> Where do you get this from? I always used [ ], and I found it >> sufficient. Why is [[ ]] faster? > > [[ ]] is faster because it is bash syntax, not a builtin command like > [ is. In most programs, both are fast enough, but you an see the > difference if you run otherwise identical tests in a loop one million > times. > >> >>> -if [ "$USECOLOR" = "YES" -o "$USECOLOR" = "yes" ]; then >>> +if [[ $USECOLOR = YES || $USECOLOR = yes ]]; then >> >> Why do you get rid of the quoting here? Quoting is nice. > > Because [[ ]] is bash syntax instead if a builtin comand, it relaxes the > usual expansion rules -- inside of [[ ]], word splitting and pathname > expansion are not performed, so you only have to quote strings if they > need to be single-quoted. > http://wiki.bash-hackers.org/syntax/ccmd/conditional_expression has more > info. > Sounds nice. This will probably mean that I will apply all the patches that do this transition - however, it might probably be nicer to squash all of those into one commit.
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