cs@xxxxxxxxxx wrote:
On 13Sep2016 16:54, todd zullinger <tmz@xxxxxxxxx> wrote:While we're at it, I might suggest that "${f%.mp4}.mp3" isn't as clear as "${f/.mp4/.mp3}" for this particular for loop.I think that's a little subjective; I personally prefer the former.
You say that like code is expressive subject to the whims of individual personalities. ;)
The pattern substitution method ${parameter/pattern/string} will also look more familiar to anyone who has used s/pattern/subst/ in vim, perl, etc, which is a small bonus.for f in *.mp4; do ffmpeg -i "$f" -c:a libmp3lame "${f/.mp4/.mp3}"; doneYeah, until you try to make it robust. Eg against a filename like "temp4-take9.mp4", which your example will transmute into "temp3-take9.mp4", not quite the plan. Whereas the "f%.mp4" thing will behave correctly because of the greedy match.
While I would use /% to be safe, this particular example wouldn't break without /% because while this ${parameter/pattern/string} syntax looks like perl, sed, or vim's s/// syntax which all take regular expressions, bash's does not.
$ f="temp4-take9.mp4"; echo "${f/.mp4/.mp3}"
temp4-take9.mp3
versus
$ f="t.mp4-take9.mp4"; echo "${f/.mp4/.mp3}"
t.mp3-take9.mp4
I tend to feel that glob-based things are better than regexp based things for filename work, most of the time. Globs are simpler (albeit less powerful) patterns and shorter and more readable and often more intuitive. (When they're enough.)
Well said.I try to avoid being too clever in any sort of coding. That helps for scripts I don't edit frequently and for code which others need to maintain with me. There's nothing like scratching your head and having to read your own code 3 times to figure out what it was doing.
(I think this is a big part of why I moved from perl to python years ago. Perl is wonderful but it seems to encourage -- or perhaps just doesn't discourage -- clever idioms. That and I hate having to type all the sigils and semicolons. ;)
Thanks to all for the question and discussion. I enjoy diversions like this. I nearly always pick up some new technique and interesting points of view.
-- Todd ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We hold that what one man cannot morally do, a million men cannot morally do, and government, representing many millions of men, cannot do. -- Auberon Herbert
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