examples/functions/recurse

   1 #!/bin/bash
   2
   3 #From: kaz@ashi.footprints.net (Kaz Kylheku)
   4 #Newsgroups: comp.os.linux.misc
   5 #Subject: Re: bash question: subdirectories
   6 #Message-ID: <slrn8a0gu9.v5n.kaz@ashi.FootPrints.net>
   7 #Date: Tue, 08 Feb 2000 16:24:35 GMT
   8
   9 #Actually it can be made to. That is to say, it is possible to code a recursive
  10 #descender function in the bash language. Here is an example.
  11 #
  12 #What is nice about this is that you can embed the function into your shell
  13 #script. The function changes the current working directory as it descends.
  14 #So it can handle arbitrarily deep paths. Whereas paths generated by the
  15 #find command can cause a problem when they get too long; the kernel has a
  16 #hard limit on the length of the string passed to the open() and other
  17 #system calls.
  18
  19 #There are races; what if the directory tree is blown away during the traversal?
  20 #The function won't be able to crawl back up using the .. link and will just
  21 #bail.
  22
  23 # Recursive Directory Traverser
  24 # Author: Kaz Kylheku
  25 # Date: Feb 27, 1999
  26 # Copyright 1999
  27
  28 # Function parameter usage:
  29 # $1 directory to search
  30 # $2 pattern to search for
  31 # $3 command to execute
  32 # $4 secret argument for passing down path
  33
  34 function recurse
  35 {
  36     local file
  37     local path
  38
  39     if [ "$4" = "" ] ; then
  40         path="${1%/}/"
  41     else
  42         path="$4$1/"
  43     fi
  44
  45     if cd "$1" ; then
  46         for file in $2; do
  47             if [ -f "$file" -o -d "$file" ]; then
  48                 eval "$3"
  49             fi
  50         done
  51         for file in .* * ; do
  52             if [ "$file" = "." -o "$file" = ".." ] ; then
  53                 continue
  54             fi
  55             if [ -d "$file" -a ! -L "$file" ]; then
  56                 recurse "$file" "$2" "$3" "$path"
  57             fi
  58         done
  59         cd ..
  60     fi
  61 }
  62
  63 recurse "$1" "$2" 'echo "$path$file"'
  64