On: Show HN: Sensible Bash: An attempt at saner Bash d...

[Symbiote]

Three things I use regularly, even in scripts:

1) Glob qualifiers:

  ls *(.)

will only match files, not directories, symlinks etc.

  ls **/*.jpg(.L-3000000on[1,5]) **/*.png(N)

will match .jpg files in the current and all subdirectories, which are:

  . files
  L-3000000 with "length" (size) under 3MB
  on ordering them numerically
  [1,5] and only the first five

plus any .png files, if they exist (N = it won't fail if they don't).

I have some scripts with expressions this complicated, but day-to-day it's useful for finding empty files (L0) or excluding directories. "man zshexpn" and search "Glob Qualifiers".

2) Glob operators:

  ls DSC<100-200>.JPG

matches files with names between DSC100.JPG to DSC200.JPG.

  setopt extended_glob
  ls *.java~*Test*

matches all .java files, except those matching Test*. Same man page, search "Glob Operators".

3) Lazy for-loops (single command doesn't require do-done), and taking two variables:

  echo "A 1" > tempfile
  for i j in $(<tempfile); echo $i $j

4) Parameter expansion.

  > x=EXAMPLE.jpg
  > echo $x:r.png ${x:r:l}.png
  EXAMPLE.png example.png

Interactively, shell history seems to be nicer, I use a couple of global aliases (alias -g L='| less'), and the completion system completes everything you can possibly think of, like usernames, hostnames, remote filenames, HTTP URLs, processes (for kill)...

[mryan → Symbiote]

Great list - I didn't know about glob operators. That glob negation is going to be very handy.

Re number 2: That works in plain old Bash too:

    ls DSC{100..200}.jpg

[Symbiote → mryan]

That's not quite the same. Zsh's <X-Y> is file globbing, only files that exist are returned. {X-Y} is parameter expansion without regard to files:

  > touch 1 3
  > ls <1-3>
  1 3
  > ls {1..3}
  cannot access 2: no such file or directory
  1 3

Nevertheless, that's a useful and more powerful alternative to seq that I didn't know about.