Bash is not alone in having built-ins that make it faster. Generally speaking, Bash is measurably slower than other shells. If you convert make your shell scrip

Bash is not alone in having built-ins that make it faster. Generally speaking, Bash is measurably slower than other shells. If you convert make your shell scripts portable and change #!/bin/bash to #!/bin/sh, in my experience, this usually makes them faster, too (on systems where sh is not bash). This is the driving factor for Debian's switch from Bash to Dash, which resulted in noticeable startup speed improvements: https://wiki.ubuntu.com/DashAsBinSh https://wiki.ubuntu.com/DashAsBinSh (Note that Systemd has since obviated most of that work.) You may be writing very different shell scripts than the ones which I encounter. I'm not sure what you mean by "variable expansion", because variable expansion is portable. Something like 98%+ of all pattern replacement I see is something simple like replacing a suffix or prefix of a string. For example, infile=input.png outfile="${infile%.png}.jpg" You can typically use sed for the complicated stuff. Above a certain level of complexity, I'd likely rewrite the script in Perl or Python, anyway. Or possibly Go.