GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
Unix |
Unix v7 |
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diff(1) |
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diff − differential file comparator
diff [ −efbh ] file1 file2
Diff tells what lines must be changed in two files to bring them into agreement. If file1 (file2) is ’−’, the standard input is used. If file1 (file2) is a directory, then a file in that directory whose file-name is the same as the file-name of file2 (file1) is used. The normal output contains lines of these forms:
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n1 a n3,n4 |
n1,n2 d n3
n1,n2 c n3,n4
These lines resemble ed commands to convert file1 into file2. The numbers after the letters pertain to file2. In fact, by exchanging ’a’ for ’d’ and reading backward one may ascertain equally how to convert file2 into file1. As in ed, identical pairs where n1 = n2 or n3 = n4 are abbreviated as a single number.
Following each of these lines come all the lines that are affected in the first file flagged by ’<’, then all the lines that are affected in the second file flagged by ’>’.
The −b option causes trailing blanks (spaces and tabs) to be ignored and other strings of blanks to compare equal.
The −e option produces a script of a, c and d commands for the editor ed, which will recreate file2 from file1. The −f option produces a similar script, not useful with ed, in the opposite order. In connection with −e, the following shell program may help maintain multiple versions of a file. Only an ancestral file ($1) and a chain of version-to-version ed scripts ($2,$3,...) made by diff need be on hand. A ’latest version’ appears on the standard output.
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(shift; cat $*; echo ´1,$p´) ⎪ ed − $1 |
Except in rare circumstances, diff finds a smallest sufficient set of file differences.
Option −h does a fast, half-hearted job. It works only when changed stretches are short and well separated, but does work on files of unlimited length. Options −e and −f are unavailable with −h.
/tmp/d?????
/usr/lib/diffh for −h
cmp(1), comm(1), ed(1)
Exit status is 0 for no differences, 1 for some, 2 for trouble.
Editing scripts produced under the −e or −f option are naive about creating lines consisting of a single ’.’.
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diff(1) | |