How to copy specific directory name to a file

Question

So I have a few directories and I want to copy only the name of the directories that start with 'k' and end with 'g' to a file. How do I do that?

Answer 1

With zsh:

print -rC1 -- k*g(N/) > dirnames.txt

Note however that since newline is as valid a character as any in a file name, that means you won't be able to distinguish two files called k1g and k2g from one file called k1g<newline>k2g.

Instead of printing those dirnames one per line, you could print them NUL-delimited by adding the -N option to print.

Then, you can post-process the resulting file with things like dirs=( ${(0)"$(<dirnames.nul-delimited)"} ) or xargs -r0a dirnames.nul-delimited some-command.

To also include the name (base name / tail) of the k*g files found in subdirectories, you'd do:

print -rNC1 -- **/k*g(ND/:t) > dirnames.nul-delimited

Note that it could have duplicates if there's both a a/king and .git/king files for instance. You could remove duplicates with:

() { print -rNC1 -- ${(u)argv} > dirnames.nul-delimited; } **/k*g(ND/:t)

An approach to have a file list that is both human readable and post-processable would be to use shell quoting around the file names:

print -rC1 -- k*g(N/:q) > dirnames.txt

Here using a zsh-specific variant of quoting. Or using a portable (in sh-like shells) and more reliable quoting syntax:

() { print -rC1 -- ${(qq)argv} > dirnames.txt; } k*g(N/)

Or using GNU ls:

ls -Ud --quoting-style=shell-always -- k*g(N/) > dirnames.txt

That list can then later be retrieved with:

dirs=( ${(Q)${(zZ[n])"$(<dirnames.txt)"}} )

In zsh.

Or in both zsh or bash (or ksh93 if you declared dirs as array first):

eval "dirs=( $(<dirnames.txt) )"

---

If you don't have or can't use zsh for some reason, but are on a GNU system, and your filenames are made on valid text in the locale, you could do something approaching with:

• print one per line (assuming file names don't contain newline characters):

  find . -mindepth 1 -maxdepth 1 -name 'k*g' -type d -printf '%f\n' |
    sort > dirnames.txt
  

• same NUL-delimited:

  find . -mindepth 1 -maxdepth 1 -name 'k*g' -type d -printf '%f\0' |
    sort -z > dirnames.txt
  

• recursive, nul-delimited:

  find . -name 'k*g' -type d -printf '%f\0' |
    sort -z > dirnames.txt
  

• same deduplicated:

  find . -name 'k*g' -type d -printf '%f\0' |
    LC_ALL=C sort -zu |
    sort -z > dirnames.txt
  

• quoted (though sorted in batches)

  find . -mindepth 1 -maxdepth 1 -name 'k*g' -type d -printf '%f\0' |
    xargs -r0 ls -d --quoting-style=shell-always --
  

• quoted and properly sorted:

  find . -mindepth 1 -maxdepth 1 -name 'k*g' -type d -printf '%f\0' |
    sort -z |
    LC_ALL=C gawk -v 'RS=\0' -v q="'" '
      shquote(s) {
        gsub(q, q "\\" q q, s)
        return q s q
      }
      {print shquote($0)}' |
    xargs -r0 ls -d --quoting-style=shell-always --
  

Answer 2

Probably best not to use ls, because of this.

Try:

find * -maxdepth 0 -type d -name 'k*g' > filename.txt

(Without -maxdepth 0 it'll also do subfolders of folders. Use -iname instead of -name if uppercase K and G should also count.)

If there's any possibility that you'll have folders or files that begin with hyphens (but who does that?) you can use this instead:

find . -maxdepth 1 -type d -name 'k*g' | sed 's/^\.\///' > filename.txt

Notice the switch from -maxdepth 0 to -maxdepth 1.

Answer 3

You can use shell globbing along with redirection:

$ ls -d k*g/ > filename.txt

This will break if you have directories whose names contain newline characters. (I think it will only pick up directories and not files, but I'm not in front of a computer to check.)