#title Recursive Maintenance Scripts

Introduction

Shell scripts can be one of the most useful tools for maintaining a Linux system. Here we'll give some simple examples of a recursive script that can be used to perform maintenance functions on an entire directory structure.

Basic structure

The basic structure of the recursive script uses a function call which in turn calls itself whenever it finds a directory. The script is run with a parameter of one or more directory names. For example:

username@systemname:~$ myscript.sh directory_name_to_process another_directory_to_process

   # the function to perform
   function recursivefunction() {
     # for every file in the directory - do something with it
     for file in "$1"/*; do
       # do something
     done
     # once you've processed all the files go back and check for directories
     for file in "$1"/*; do
       # if you find a directory...
       if [ -d "$file" ]; then
         # perhaps do something
         # then call the function again with this new directory
         recursivefunction "$file"
       fi
     done
   }

   for param in "$@"; do
     recursivefunction "$param"
   done

Examples

Correcting file permissions

Have you ever copied a directory structure from a CDROM or USB thumb drive and the file and directory permissions were a mess? This quick script can recurse through the directory structure and set some sane permissions.

   function setperms() {
     for file in "$1"/*; do
       chmod 664 "$file"
     done
     for file in "$1"/*; do
       if [ -d "$file" ]; then
         chmod 775 "$file"
         setperms "$file"
       fi
     done
   }

   for param in "$@"; do
     setperms "$param"
   done

Convert all video files

Want to convert all your various video files to the open standard Ogg Theora format?

   function converttoogg() {
     for file in "$1"/*.mpg; do
       chmod 660 "$file"
       ffmpeg2theora -v 10 -a 10 "$file"
     done
     for file in "$1"/*.avi; do
       chmod 660 "$file"
       ffmpeg2theora -v 10 -a 10 "$file"
     done
     for file in "$1"/*.vob; do
       chmod 660 "$file"
       ffmpeg2theora -v 10 -a 10 "$file"
     done
     for file in "$1"/*.wmv; do
       chmod 660 "$file"
       ffmpeg2theora -v 10 -a 10 "$file"
     done
      for file in "$1"/*.mov; do
       chmod 660 "$file"
       ffmpeg2theora -v 10 -a 10 "$file"
     done
    for file in "$1"/*; do
       if [ -d "$file" ]; then
         chmod 770 "$file"
         converttoogg "$file"
       fi
     done
   }

   for param in "$@"; do
     converttoogg "$param"
   done