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31 .\" @(#)cmp.1 8.1 (Berkeley) 6/6/93
33 .Dd September 23, 2021
43 .Op Fl -ignore-initial Ns Cm = Ns Ar num1 Ns Op :num2
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
61 .It Fl b , Fl -print-bytes
62 Print each byte when a difference is found.
64 Do not follow symbolic links.
65 .It Fl i Ar num1 Ns Oo :num2 Oc , Fl -ignore-initial= Ns Ar num1 Ns Op :num2
76 is not specified, then
82 .It Fl l , Fl -verbose
83 Print the byte number (decimal) and the differing
84 byte values (octal) for each difference.
85 .It Fl n Ar num , Fl -bytes= Ns num
89 .It Fl s , Fl -silent , Fl -quiet
90 Print nothing for differing files; return exit
95 but prints in hexadecimal and using zero as index
96 for the first byte in the files.
98 For regular files compare file sizes first, and fail the comparison if they
102 The optional arguments
106 are the byte offsets from the beginning of
110 respectively, where the comparison will begin.
111 The offset is decimal by default, but may be expressed as a hexadecimal
112 or octal value by preceding it with a leading ``0x'' or ``0''.
117 may also be specified with SI size suffixes.
121 utility exits with one of the following values:
124 The files are identical.
126 The files are different; this includes the case
127 where one file is identical to the first part of
129 In the latter case, if the
131 option has not been specified,
133 writes to standard error that EOF was reached in the shorter
134 file (before any differences were found).
139 Assuming a file named
141 with the following contents:
142 .Bd -literal -offset indent
150 .Bd -literal -offset indent
151 $ echo -e "a\\nb\\nc" | cmp - example.txt
154 Same as above but introducing a change in the third byte of stdin.
155 Show the byte number (decimal) and differing byte (octal):
156 .Bd -literal -offset indent
157 $ echo -e "a\\nR\\nc" | cmp -l - example.txt
161 Compare file sizes of
164 .Pa /boot/loader.conf
165 and return 1 if they are not equal.
168 can only be used with regular files:
169 .Bd -literal -offset indent
170 $ cmp -z example.txt /boot/loader.conf
171 example.txt /boot/loader.conf differ: size
176 omitting the first 4 bytes from stdin and the first 2 bytes from
178 .Bd -literal -offset indent
179 $ echo -e "a\\nR\\nb\\nc" | cmp - example.txt 4 2
187 utility is expected to be
198 options are extensions to the standard.
202 arguments are extensions to the standard.
211 above refers to the traditional power of two convention, as described in
212 .Xr expand_number 3 .