Diff on Amit Agarwal Linux Blog

meld – cvs diff with ease

Wed, 17 Oct 2012 01:15:01 +0000

Visualization of the “history tree” of a revision controlled project, showing branching, merging, tagging, etc. (Photo credit: Wikipedia)

There are couple of ways to make life easier with CVS diff. But here is one that is really good.
First if you haven’t, install meld:

sudo yum install meld

meld is basically a diff viewer and pretty good at it 😉

Compare files excluding certain lines.

Tue, 18 Oct 2011 11:12:15 +0000

Quick tip, you can use any expression for the sed commands in the (). With this trick you can redirect the stdout of 2 commands to the diff command. This might become very useful, if you want to compare 2 files, excluding the first line.

diff <(sed '1d' file) <(sed '1d' file2)

More interesting example is where the string ABC is converted to abc before comparing in the second file with the following command:

Find out why a program can't seem to access to a file

Wed, 05 May 2010 15:19:18 +0000

$ strace php tias.php -e open,access 2>&1 | <a class="zem_slink freebase/en/grep" href="http://en.wikipedia.org/wiki/Grep" title="Grep" rel="wikipedia">grep foo.txt Sometimes a program refuses to read a file and you’re not sure why. You may have display_errors turned off for <a class="zem_slink freebase/en/php" href="http://www.php.net/" title="PHP" rel="homepage">PHP or something. In this example, fopen(’/var/www/test/foo.txt’) was called but doesn’t have read access to foo.txt.

Strace can tell you what went wrong. E.g., if php doesn’t have read access to the file, strace will say ”EACCESS (Permission denied)”. Or, if the <a class="zem_slink freebase/guid/9202a8c04000641f8000000000220ffa" href="http://en.wikipedia.org/wiki/Path_%28computing%29" title="Path (computing)" rel="wikipedia">file path you gave doesn’t exist, strace will say ”ENOENT (No such file or directory)”, etc.

Diff Linux command — Find the difference in files the easier way.

Thu, 17 Sep 2009 16:12:24 +0000

In Linux you can use diff command to find the differences in file.

What is interesting is that you can use ”diff -u” to list the differences with ’+’ and ’-’ rather than sometimes confusing ’>’ and '<’.

Running the regular diff between two text files to see the differences is not so elegant for the human eye to decode. Luckily there are plenty of tools out there to make this easy.