cmp(1) — Commands
NAME
cmp − Compares two files
SYNOPSIS
cmp [-l | -s] file1 file2
The cmp command compares two files.
FLAGS
-lPrints the byte number (decimal) and the differing bytes (octal) for each difference.
-sDoes not print data for differing files; returns only an exit value.
DESCRIPTION
If file1 is - (dash), standard input is used. By default, the cmp command prints no information if the files are the same. If the files differ, cmp prints the byte and line number where the difference occurred. The cmp command also specifies whether one file is an initial subsequence of the other (that is, if the cmp command reads an End-of-File character in one file before finding any differences). Normally, you use the cmp command to compare nontext files and the diff command to compare text files.
Note that bytes and lines reported by cmp are numbered from 1.
EXAMPLES
1.To determine whether two files are identical, enter:
cmp prog.o.bak prog.o
The preceding command compares the files prog.o.bak and prog.o. If the files are identical, a message is not displayed. If the files differ, the location of the first difference is displayed. For instance:
prog.o.bak prog.o differ: byte 5, line 1
If the message cmp: EOF on prog.o.bak is displayed, then the first part of prog.o is identical to prog.o.bak, but there is additional data in prog.o. If the message cmp: EOF on prog.o is displayed, it is prog.o.bak that is the same as prog.o but also contains addition data.
2.To display each pair of bytes that differ, enter:
cmp -l prog.o.bak prog.o
This compares the files and then displays the byte number (in decimal) and the differing bytes (in octal) for each difference. For example, if the fifth byte is octal 101 in prog.o.bak and 141 in prog.o, then the cmp command displays:
5 101 141
.
.
EXIT VALUES
Exit value 0 is returned for identical files, 1 for differing files, and >1 for an inaccessible file or a missing argument.