I've been using shell scripts for a long time, mainly leveraging tools like grep, sed, and awk for quick text parsing and analysis. Recently, I wrote a larger shell script that's processing around 1,000 items, but I've noticed it's running slower than I'd like. I've traced the lag to how I'm looping through each line of input in Bash. My processing logic isn't extensive, but it's clear that it's noticeably slower compared to similar Python code. For example, even simply echoing each line with a while loop takes about 2 seconds, while the same job in Python only takes around 30 milliseconds. I'm considering converting my tool to Python for efficiency but wanted to see if anyone has ideas to speed it up in Bash before I make that leap.
6 Answers
It sounds like you're hitting some performance limits with Bash loops. Have you tried using `xargs`, `parallel`, or even `forkrun`? Those might help cut down the processing time considerably since they're designed to handle batch processing more efficiently. Bash is great for scripting but can struggle with heavy looping tasks.
Your performance seems extremely slow for just processing a few hundred lines! Maybe there’s something else dragging down your Bash? Are you running a minimal shell environment? I've done empty loops over 250,000 lines in under 4 seconds on older hardware! It might be worth isolating your script from any potential interference.
Ever considered using MAWK for your processing? It's surprisingly efficient for text tasks if you can adapt your logic to fit it.
Using `MAPFILE` might help speed up your script a bit. It’s not the same as memory mapping a file, but it could process your input more efficiently. Just keep in mind that converting your script with something like SHC might not really boost performance; it's more about protecting your code than speeding it up.
True! SHC just encrypts the script; it doesn’t actually optimize execution speed or anything.
Have you tested with minimal commands to isolate the issue? It seems like there's something else affecting your runtime, especially with your Bash setup being pretty clean.
I’ve tried with minimal setups, and while I got decent speeds, it’s still way slower than expected compared to Python.
If there's a lot of processing happening for each line, could this be affecting your speed? Each `grep` or `cut` call in your loop could be adding up. You might want to batch those commands or do some of that processing inside a single pass rather than having it run multiple times for every line.
Yeah, I ran a test with a simple command and it took much longer than expected. It really made me rethink how frequent external commands in loops affect performance!
Totally, `MAPFILE` is handy. Just remember, it’s literally the same as `readarray`, so you might just want to stick with one for clarity!