Open System Services Shell and Utilities Reference Manual (G06.28+, H06.05+)

User Commands (c) cmp(1)
NAME
cmp - Compares two files
SYNOPSIS
cmp [-l | -s] file1 file2
The cmp command compares two files.
FLAGS
-l Prints the byte number (in decimal) and the differing bytes (in octal) for each
difference.
-s Does not print data for differing files; returns only an exit value.
DESCRIPTION
If the file1 or file2 argument is specified as a - (dash), the standard input file 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. The first differing byte number
is from file1, and the second is from file2.
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 ident-
ical, a message is not displayed. If the files differ, the location of the first difference is
displayed as follows:
prog.o.bak prog.o differ: char 5, line 1
If the message cmp: EOF on prog.o.bak is displayed, the first part of prog.o is ident-
ical to prog.o.bak, but there is additional data in prog.o. If the message cmp: EOF on
prog.o is displayed, prog.o.bak that is identical to prog.o but that also contains addi-
tional data.
2. To display each pair of bytes that differ, enter:
cmp -l prog.o.bak prog.o
This command 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
file prog.o.bak and 141 in file prog.o, then the cmp command displays:
5 101 141
.
.
EXIT VALUES
Exit value 0 (zero) is returned for identical files, 1 for differing files, and 2 for an inaccessible
file, a missing argument, or some other error.
RELATED INFORMATION
Commands: comm(1), diff(1).
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