Linux – Difference in whitespace between two files on Linux

diff()linuxwhitespace

I have two files that when I compare with diff show that every line has changed. When I compare them with diff -w (ignoring whitespace) it shows the few minimal changes that I expect.

Obviously there is some difference between the whitespace in each file, but I don't know what they are or how to find them. I have tried editing the files to ensure that the whitespace is actually space characters (as opposed to tabs) but am unsure what else to do.

I have used vim with :set list on to confirm there was no trailing space at the end of the lines.

I also believe that each file has Linux line terminators as vim didn't show the ^M at the end of the lines.

Best Answer

For vim users, there is a handy utility to show exact differences between files:

vimdiff file1 file2

This will put each file in windows, side-by-side, and differences with highlighted in color.

Some useful commands when in vimdiff

While in vimdiff, some useful commands are:

  • ]c: jump to next change

  • [c: jump to previous change

  • ctrl-W ctrl-W: switch to other window

  • zo: open folds

  • zc: close folds

Example

Here is an example of vimdiff in an xterm comparing two versions of a cups configuration file:

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You can see that long sections of identical lines have been collapsed. They can be opened again with zo.

The color scheme will vary depending on your option settings. In the above example, when a line appears in one file but not the other, that line is given a dark blue background. In the other file, the missing lines are indicated by dashed lines. When a line appears in both files but has some differences, the unchanged parts of the lines have a pink background and the changed parts have a red background.

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