Command-Line – Run a Command on All Subfolders

command linedirectoryfileswildcards

If you have a series of subfolders (like from a to z) and want to run a command on each one of them (like rm *.pdf or ls *.pdf), how do you do that? The "manual" approach would be cd a, rm *.pdf, or ls *.pdf, cd .., cd b, … That seems too complicated, so I believe there must be an easier approach.

Best Answer

Try doing this (using bash, brace expansion & globs):

rm -f {a..z}/*.pdf

rm -f [a-z]/*.pdf

if your shell lack the brace expansion feature.

Contrary to [a-z], {a..z} (also supported by ksh93) is not a glob, it's brace expansion, it's expanded (before globs) regardless of whether files exist or not. That's like rm -f a/*.pdf b/*.pdf..., regardless of whether a, b... exist or not. Also note that contrary to [a-z] where the range may be locale dependant (like may include é, ś...), {a..z} only works with byte ranges (and reliably only in the ASCII letter ranges, and number ranges)

(Merci Stephane Chazelas for explanations)

Related Solutions

Shell Script – Distributing Thousands of Files Over Subfolders

With zsh:

autoload zmv
zmv 'file_(<->)' 'S_$((1 + ($1 - 1) / 100))'

If the files are not numbered, but you just want to split that list:

n=0; zmv -Q 'file_*(n)' 'S_$((n++/100+1))'

(n) is to toggle numerical ordering for the list (and you need -Q for that globbing qualifier).

Those call one mv per file. You can make it a bit more efficient by making mv builtin (zmodload zsh/files), or you could do:

files=(file_*(nN))
for ((n=1; $#files; n++)) {
  mv -- $files[1,100] S_$n
  files[1,100]=()
}

The (nN) above are zsh globbing qualifiers which further qualify the glob. n is for numerical sorting, N is to turn on the nullglob option for that glob, that is for the glob to expand to an empty list when there is no match.

(with that one, you could even throw in a mkdir S_$n in case those directories didn't exist beforehand).

Bash – Read all files in folder and subfolders – progress and size

Not sure I understand your question fully, but what about:

find . -type f -exec pv -N {} {} \; > /dev/null

Gives an output like:

  ./file1:  575kB 0:00:00 [1.71GB/s] [=======================>] 100%
  ./file2: 15.2GB 0:00:07 [2.22GB/s] [==>                      ] 15% ETA 0:00:38

Best Answer

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Shell Script – Distributing Thousands of Files Over Subfolders

Bash – Read all files in folder and subfolders – progress and size

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