How can I diff two config files?
Solution 1
diff <(grep -v '^#' f1) <(grep -v '^#' f2)
To avoid blank lines, and lines containing nothing but spaces, in addition to identical lines that have a single difference of added leading spaces...
diff -b \
<(grep -vE '^([ \t]*#|^[ \t]*$)' f1)\
<(grep -vE '^([ \t]*#|^[ \t]*$)' f2)
By this point though, I'd probably put that into a script and write something like the original suggestion that's a little more readable.
Solution 2
If you are somewhat comfortable with vim, I would strongly encourage you to use vimdiff:
vimdiff file1 file2
This will open a vim session with two panes, with one file on each side. Highlights and color will indicate differences between the files, and all identical parts will be hidden (folded, but expandable).
Then, if you want to selectively merge differences from one file to the other, you can use the following commands:
(Consider the "current file" to be the one where the cursor is)
^W^W to change focus from one file's window to the other file's window
]c to advance to the next block with differences
[c to reverse search for the previous block with differences
do (diff obtain) to bring changes from the other file to the current file
dp (diff put) to send changes from the current file to the other file
Note: Both do and dp work if you are on a block or just one line under a block.
u to undo
zo to unfold/un-hide text
zc to re-fold/re-hide text
zr will unfold both files completely (use :help fold for more about folding )
:diffupdate will re-scan the files for changes
As you start moving changed text over or bringing changes in, the now-identical parts of the files will automatically fold, too.
When you are finished, you can quit and write both files with :xa!
You can also write, quit, discard changes, etc., one pane at a time just as you would normally do with vim.
You can use all the common vim commands to edit the files at will ; I've only described the most common and useful commands you're likely to use in a vimdiff session (as opposed to a generic vim one).
Solution 3
Beyond Compare is the ultimate tool for this!
Link: http://www.scootersoftware.com/
Available for Windows and Linux.
Jeff wrote a good overview article about the tool awhile back:
http://www.codinghorror.com/blog/archives/000454.html
Solution 4
Expanding on nima's one-liner, you could do that as a shell function and drop it in your .bashrc
diff <(grep -v '^#' f1) <(grep -v '^#' f2)
becomes (using -u because I like unified diffs)
function cleandiff {
diff -u <(grep -v '^#' $1| grep -v '^ *$') <(grep -v '^#' $2 | grep -v '^ *$')
}
If you like GUI diff viewers, meld is nice, and understands revision controlled dirs/files.
Solution 5
After cleaning the comments, I would advise using KDiff3, it's a pretty good diff/merge tool and you dont need vim fu to use it :)
Related videos on Youtube
Comments
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jldugger almost 2 years
I've got two snmpd.conf files, one on a server that works, and one that doesn't. How can I diff the two config files while stripping out irrelevant comments and newlines?
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Xerxes about 15 yearsWatch out jldugger! You're about to
level
! =) -
AnonymousLurker over 11 yearsIt is really a bad idea to strip comments, how do you know they are irrelevant without looking at them?
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Clinton Blackmore about 15 yearsBeyond Compare is awesome!
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Govindarajulu about 15 years+1 for providing a single-line solution
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henkojinko about 15 yearsis this available on *nix systems?
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Mark Norgren about 15 yearsBeyond Compare 3 does not run as a console application on Linux. It requires X-Windows. Supported Linux distributions (32-bit) Red Hat Enterprise Linux 4, 5 Fedora 4 - 10 Novell Suse Linux Enterprise Desktop 10 openSUSE 10.3, 11 Ubuntu 6.06 - 8.10 Not Tested Any 64-bit Linux kernel Not Compatible Red Hat Enterprise Linux 3
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Avery Payne about 15 years+1 for meld, which has made graphical diff'ing sooo much more easy.
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Zoredache about 15 years@jldugger, try updating the grep to be like this to exclude comments and whitespace. - egrep -v '^(#.*|)$'
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Jpsy over 9 yearsI couldn't live without this tool anymore! An extreme time saver. When I changed from PC to Mac about 1 year ago I was very happy to find that it had just been ported to Mac too.