cmp (Unix)

cmp is a command line utility for computer systems that use Unix or a Unix-like operating system. It compares two files of any type and writes the results to the standard output. By default, cmp is silent if the files are the same; if they differ, the byte and line number at which the first difference occurred is reported.

Switches

cmp may be qualified by the use of command-line switches. The switches supported by the GNU version of cmp are:

-b, --print-bytes 

Print differing bytes.

-i SKIP, --ignore-initial=SKIP 

Skip the first SKIP bytes of input.

-i SKIP1:SKIP2, --ignore-initial=SKIP1:SKIP2 

Skip the first SKIP1 bytes of FILE1 and the first SKIP2 bytes of FILE2.

-l, --verbose 

Output byte numbers and values of all differing bytes.

-n LIMIT, --bytes=LIMIT 

Compare at most LIMIT bytes.

-s, --quiet, --silent 

Output nothing; yield exit status only.

-v, --version 

Output version info.

--help 

Outputs a help file.

Return values

• 0 - files are identical
• 1 - files differ
• 2 - inaccessible or missing argument

See also

• Comparison of file comparison tools
• List of Unix programs

References

External links

• cmp: compare two files – Commands & Utilities Reference, The Single UNIX® Specification, Issue 7 from The Open Group
• Comparing and Merging Files: Invoking cmp The section of the manual of GNU cmp in the diffutils free manual.