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I wrote an bash enumerator because I was sick of xargs
21–30 of 202 posts
Re: I wrote an bash enumerator because I was sick of xargs
#22Earlier quoted context omitted.
why would you ever pipe find into xargs instead of calling -exec? find -exec the '{}' iterated command ';'
Because xargs is faster. Exec will invoke the command once per matching file (which is sometimes what you want, of course)! While xargs will accumulate a bunch of file names, then when it as n names will invoke the command with those names, while continuing to accumulate names until n is reached or the pipe closes. The size of n depends on the system, but is usually at least a thousand.
the example as given does not accumulate, so that is what i worked with.
find -exec command '{}' '+'
Re: I wrote an bash enumerator because I was sick of xargs
#23Earlier quoted context omitted.
why would you ever pipe find into xargs instead of calling -exec? find -exec the '{}' iterated command ';'
Because xargs is faster. Exec will invoke the command once per matching file (which is sometimes what you want, of course)! While xargs will accumulate a bunch of file names, then when it as n names will invoke the command with those names, while continuing to accumulate names until n is reached or the pipe closes. The size of n depends on the system, but is usually at least a thousand.
The prior has a point because 98.89% of the time I type xargs -n 1 -0 and we are deep in the useless pipe argument which Rob Pike amongst others has rehearsed well.
I do it because I do it, just like why I use egrep and sed in pipes along with awk.
Re: I wrote an bash enumerator because I was sick of xargs
#24I have found that the most reliable way I like is to just construct the command externally and then pass to gnu parallel (mostly for --eta and --tmuxpane). And the great thing is, as others say, xargs -I. I prefer for shortness (and few collisoins), '@'
seq 1 10|xargs -I@ echo 'bash run.py @'|parallel -j 10
I know the echo is a little silly but then I can remove the |parallel and see if it's right. And if I don't want parallelism, I just pass to bash
Re: I wrote an bash enumerator because I was sick of xargs
#25in zsh you can just write: for x (*.sh); echo "before $x after" or for x in *.sh; echo "before $x after" or for x (*.sh) { echo -n "before "; echo -n $x; echo " after" }
missed the point. reason to use xargs or parallel are generally two: list of arguments is too long, or list of arguments that is kept in memory would take too much
for example
for a in `find / ` ; do echo $a ; done
Re: I wrote an bash enumerator because I was sick of xargs
#26I feel like it could be just alias to some particular GNU Parallel set of options
Re: I wrote an bash enumerator because I was sick of xargs
#27find -print0 | xargs -0 -I {} "the {} iterated command"
why would you ever pipe find into xargs instead of calling -exec? find -exec the '{}' iterated command ';'
Leah Neukirchen's lr and xe are very nice as a find and xargs replacement (although lr's test flag is way too complex). lr *.file | xe -s ' ... ' is a really great pattern for iterative scripting and hard to get wrong.
Re: I wrote an bash enumerator because I was sick of xargs
#28Earlier quoted context omitted.
Because xargs is faster. Exec will invoke the command once per matching file (which is sometimes what you want, of course)! While xargs will accumulate a bunch of file names, then when it as n names will invoke the command with those names, while continuing to accumulate names until n is reached or the pipe closes. The size of n depends on the system, but is usually at least a thousand.
the example as given does not accumulate, so that is what i worked with. find -exec command '{}' '+' accumulates file arguments too. the only advantage of xargs is that you can tell it how many arguments to accumulate,̶ ̶t̶h̶e̶ ̶d̶o̶w̶n̶s̶i̶d̶e̶ ̶o̶f̶ ̶x̶a̶r̶g̶s̶ ̶i̶s̶ ̶t̶h̶a̶t̶ ̶y̶o̶u̶ ̶h̶a̶v̶e̶ ̶t̶o̶ ̶s̶p̶e̶c̶i̶f̶y̶ ̶t̶h̶e̶ ̶n̶u̶m̶b̶e̶r̶,̶ ̶w̶h̶e̶r̶e̶a̶s̶ ̶f̶i̶n̶d̶ ̶j̶u̶s̶t̶ ̶f̶i̶t̶s̶ ̶a̶s̶ ̶m̶a̶n̶y̶ ̶a̶s̶ ̶i̶t̶ ̶c…
xargs will fit as many as it can in 128 KiB or the system limit, which is smaller, so in practice, it's almost always pretty similar default packing
Re: I wrote an bash enumerator because I was sick of xargs
#29in zsh you can just write: for x (*.sh); echo "before $x after" or for x in *.sh; echo "before $x after" or for x (*.sh) { echo -n "before "; echo -n $x; echo " after" }
missed the point. reason to use xargs or parallel are generally two: list of arguments is too long, or list of arguments that is kept in memory would take too much for example for a in `find / ` ; do echo $a ; done will take A LOT of memory, while using find's -exec, xargs, or parallel will not
But bashenumerate doesn't do that? The parent is saying you should zsh shortloops instead of bashenumerate not zsh shortloops instead of xargs.
Re: I wrote an bash enumerator because I was sick of xargs
#30I use:
find . -name '*.log' -print0 | xargs -0 rm
This null termination is now a POSIX standard.