posix shell tips
Tricks for increasing performance or acheiving unusual goals in POSIX shell scripts.
grep is pretty great by default but sometimes you just need to check if a string is present in a file:
if [ ! grep -Fq $string $filename ]; then ...
-F does a literal search instead of a regex search, so it will use less CPU time.
If you've got an "array" of strings separated by spaces, you can avoid forking into
awk to get a field:
set -- $array first=$1 second=$2
You will lose access to the arguments passed to your function or script though.