To find the difference between 02 files in Linux, use the diff command. In nutshell, diff compares the contents of the two files from-file and to-file.Syntax: diff [options] from-file to-file2 The following options can be used with diff command:
| -b | Ignore changes in amount of white space. |
| -B | Ignore changes that just insert or delete blank lines. |
| -i | Ignore changes in case; consider upper- and lower-case letters equivalent. |
| –new-file | In directory comparison, if a file is found in only one directory, treat it as present but empty in the other directory. |
| -r | When comparing directories, recursively compare any subdirectories found. |
Example:Suppose you have a file ‘file1.txt‘:
and another file ‘file2.txt‘:
Now, if you execute the diff command ‘diff file1.txt file2.txt‘, then it will display the output like this:
Lines “1d0” and “6a6” are the coordinates and types of the differences between the two compared files, while lines like “< aa” and “> kk” are the differences themselves. Diff change notation includes 2 numbers and a character between them. Characters tell you what kind of change was discovered:
a – line added
c – line changed
d – line deleted
Left number of the character defines the line number in the first file, and Right number of the character defines the line number in the second file.Output details:
| 1d0 < aa |
It means that 1 line was deleted. < aa denotes that the aa line is present only in the first file. |
| 3c2 < cc — > kk |
It means that the line#3 has changed from “cc”[in first file] to “kk”[in second file]. |
| 6a6 > gg |
It means that one new line added in the second file, it’s “gg” at line#7. |