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31 .\" @(#)cmp.1 8.1 (Berkeley) 6/6/93
34 .Dd September 23, 2021
44 .Op Fl -bytes Ns Cm = Ns Ar num
46 .Op Ar skip1 Op Ar skip2
50 utility compares two files of any type and writes the results
51 to the standard output.
54 is silent if the files are the same; if they differ, the byte
55 and line number at which the first difference occurred is reported.
57 Bytes and lines are numbered beginning with one.
59 The following options are available:
60 .Bl -tag -width indent
62 Do not follow symbolic links.
63 .It Fl l , Fl -verbose
64 Print the byte number (decimal) and the differing
65 byte values (octal) for each difference.
66 .It Fl n Ar num , Fl -bytes= Ns num
70 .It Fl s , Fl -silent , Fl -quiet
71 Print nothing for differing files; return exit
76 but prints in hexadecimal and using zero as index
77 for the first byte in the files.
79 For regular files compare file sizes first, and fail the comparison if they
83 The optional arguments
87 are the byte offsets from the beginning of
91 respectively, where the comparison will begin.
92 The offset is decimal by default, but may be expressed as a hexadecimal
93 or octal value by preceding it with a leading ``0x'' or ``0''.
98 may also be specified with SI size suffixes.
102 utility exits with one of the following values:
105 The files are identical.
107 The files are different; this includes the case
108 where one file is identical to the first part of
110 In the latter case, if the
112 option has not been specified,
114 writes to standard error that EOF was reached in the shorter
115 file (before any differences were found).
120 Assuming a file named
122 with the following contents:
123 .Bd -literal -offset indent
131 .Bd -literal -offset indent
132 $ echo -e "a\\nb\\nc" | cmp - example.txt
135 Same as above but introducing a change in the third byte of stdin.
136 Show the byte number (decimal) and differing byte (octal):
137 .Bd -literal -offset indent
138 $ echo -e "a\\nR\\nc" | cmp -l - example.txt
142 Compare file sizes of
145 .Pa /boot/loader.conf
146 and return 1 if they are not equal.
149 can only be used with regular files:
150 .Bd -literal -offset indent
151 $ cmp -z example.txt /boot/loader.conf
152 example.txt /boot/loader.conf differ: size
157 omitting the first 4 bytes from stdin and the first 2 bytes from
159 .Bd -literal -offset indent
160 $ echo -e "a\\nR\\nb\\nc" | cmp - example.txt 4 2
168 utility is expected to be
177 options are extensions to the standard.
181 arguments are extensions to the standard.
190 above refers to the traditional power of two convention, as described in
191 .Xr expand_number 3 .