The internal bash parameter expansion functions (e.g. ${line%% *}) tend to be
quite inefficient. Here is one example, compare the performance of bash
substitution to Perl substitution:
#!/bin/bash
comma_sep=$(perl -e 'for($i=0;$i<1000;$i++) { print("$i;") };')
time space_sep=${comma_sep//;/ }
time space_sep=$(echo $comma_sep | perl -pe 's/;/ /g')
On my machine, the times look like this:
Bash:
real 0m2.140s
user 0m2.049s
sys 0m0.002s
Perl:
real 0m0.007s
user 0m0.010s
sys 0m0.002s
I got burned more than once by unexpected inefficiencies in bash. As others
have said, Perl is very fast and reliable for large text manipulations.
(The script is just an example to show the point. Replacing commas with spaces
through substitution is not a good idea. Transliteration will do the job
faster.)
HTH,
Tomas
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