#!/bin/sh
# Created by Wojtek Jamrozy (www.wojtekrj.net)
mv $1 cop_$1
mv $2 $1
mv cop_$1 $2

Note: There is a file embedded within this post, please visit this post to download the file.
Download this file or make a text file with this content named swap and make it executable with command

chmod +x swap

Then copy this file to /usr/local/bin directory using:

cp swap /usr/local/bin

If you have this file in /usr/local/bin directory (or any other included in $PATH environment variable – command

echo $PATH

will show other directories) you don’t have to write full path to script:

swap f1 f2

will swap contents of files f1 and f2.
Example of usage in shell:

wojtekrj@wojtek-laptop:~$ echo "File 1" > file1 && echo "File 2" > file2
wojtekrj@wojtek-laptop:~$ cat file1
File 1
wojtekrj@wojtek-laptop:~$ cat file2
File 2
wojtekrj@wojtek-laptop:~$ swap file1 file2
wojtekrj@wojtek-laptop:~$ cat file1
File 2
wojtekrj@wojtek-laptop:~$ cat file2
File 1

#!/bin/sh

is a standard header, which helps bash shell recognize file as a bash script.

mv file1 file2

a command, which rename/move file from path file1 to file2

cat file

show content of file

When the script is executed with two arguments (like in example – swap f1 f2), $1 will contain first argument – f1, and $2 second – f2.
When $1 or $2 appears in script, it’s replaced with content of $1 or $2:

mv $1 cop_$1 -> mv f1 cop_f1
mv $2 $1 -> mv f2 f1

echo text_to_display

echo "text_to_display"

commands will show text text_to_display

command > file

will save output of command to file file

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Firstly, I’ve installed Samba, a good tool for managing it – gsambad and smbfs (mount and umount commands for the smbfs). You can use NFS instead of samba if you want. Then, I’ve made my “changed” data directory accessible for another computer.
Lets assume, that /data is “unchanged” data directory on second computer, and /datarem is mounted “changed” data directory from first computer. You can mount this directory using for example:

sudo mount -t smbfs -o iocharset=utf8,username="TYPE_SMB_USER",password="TYPE_PASS" //192.168.2.15/data /datarem

Then you can use my script mov.py with following usage:

./mov.py changed_directory directory_to_update

for example:

./mov.py /datarem /data

The script will scan /datarem recursively for files and directories. If corresponding file or directory doesn’t exist in /data, it will be created. If size of file in /datarem is different to a size of corresponding file in /data, the file in /data will be replaced. If sizes are equal, file in /data is keep unchanged (it doesn’t matter for me, but for some usages it may be a problem).

Here is code:

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#! /usr/bin/env python
# Created by Wojtek Jamrozy (www.wojtekrj.net)
import os, sys, shutil
 
def update(start, end):
	if os.path.isdir(start):
		for f in os.listdir(start):
			s_ = os.path.join(start, f)
			e_ = os.path.join(end, f)
			if os.path.isdir(s_) and not os.path.exists(e_):
				os.mkdir(e_)
				print "Directory " +e_+" has been created\n"
			update(s_,e_)
	else:
		if os.path.exists(end):
			if os.path.getsize(start) != os.path.getsize(end):
				shutil.copyfile(start,end)
				print "File " +end+" has been updated\n"
		else:
			shutil.copyfile(start,end)
			print "File " +end+" has been created\n"
st = sys.argv[1]
en = sys.argv[2]
if not os.path.exists(st):
	print "Source directory does not exist!"
	sys.exit()
if os.path.isdir(st) and not os.path.exists(en):
	os.mkdir(en)
update(st,en)

You can download it here:
Note: There is a file embedded within this post, please visit this post to download the file.

Most functions used in this script are easy to understand. You can find further information here:
http://docs.python.org/lib/module-os.path.html
http://www.python.org/doc/current/lib/module-shutil.html
http://docs.python.org/lib/module-sys.html

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