Shell Programming and Scripting

Readers should be aware that if you have a really big directory with thousands of files, the shell expansion might fail or take a very long time. It may also be that the internal ls command runs out of memory, in which case, you can revert to the find method.

It would make much less difference if the task were a heavy one. If the external commands have a lot of work to do, the overhead in calling them is comparatively small.

If their task is lightweight, almost all the time they take is spent on creating a new process for each command rather than performing the actions they are asked to do.

Three external commands is not virtually nil; the shell-only method is. Creating new processes is slow; using the shell's internal capabilities is fast.

I don't know what kind of computer you're using; on mine, it's virtually nil for the task the original poster described. "Slow" is a relative term, and is ultimately a question of user acceptability. In cases where it's acceptable and I feel like it, I use external commands. The speed is quite acceptable, as I'm sure it would be for the original poster. However, your objections are duly noted and will be given the consideration they deserve.

The kind of computer you or I have is irrelevent. When giving advice in a public forum, you may be talking to people using anything from a PII at 300MHz (or less) to the latest and greatest.

Virtually nil in realtime, for one instance, is still orders of magnitude slower than using the shell.

It is probably acceptable for one-time use at the command line.

In a script, where it may be executed many times, it may cause the script to be annoyingly and unnecessarily slow, particularly if the script contains many such inefficient constructs.

I'm sure that's all perfectly well understood by all involved. It still doesn't matter in the case at hand. Sorry, I really just don't care about "orders of magnitude" (a dubious claim, besides) if the difference is imperceptible. However, the user has a variety of functional options to choose from, and reiterating your original criticism yet again (and again...) really doesn't contribute. I understood your point at the first, and I fully appreciate the difference in speed between internal and external commands. In this particular, lightweight, tiny case, I just don't care. I look forward to your virtually inevitable reply...

Can we try for the SLOWEST command??

What, no rules? Can everything be prepended by 'sleep 600000 ; '?