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31 .\" @(#)cmp.1 8.1 (Berkeley) 6/6/93
34 .Dd September 23, 2021
44 .Op Fl -ignore-initial Ns Cm = Ns Ar num1 Ns Op :num2
45 .Op Fl -bytes Ns Cm = Ns Ar num
47 .Op Ar skip1 Op Ar skip2
51 utility compares two files of any type and writes the results
52 to the standard output.
55 is silent if the files are the same; if they differ, the byte
56 and line number at which the first difference occurred is reported.
58 Bytes and lines are numbered beginning with one.
60 The following options are available:
61 .Bl -tag -width indent
62 .It Fl b , Fl -print-bytes
63 Print each byte when a difference is found.
65 Do not follow symbolic links.
66 .It Fl i Ar num1 Ns Oo :num2 Oc , Fl -ignore-initial= Ns Ar num1 Ns Op :num2
77 is not specified, then
83 .It Fl l , Fl -verbose
84 Print the byte number (decimal) and the differing
85 byte values (octal) for each difference.
86 .It Fl n Ar num , Fl -bytes= Ns num
90 .It Fl s , Fl -silent , Fl -quiet
91 Print nothing for differing files; return exit
96 but prints in hexadecimal and using zero as index
97 for the first byte in the files.
99 For regular files compare file sizes first, and fail the comparison if they
103 The optional arguments
107 are the byte offsets from the beginning of
111 respectively, where the comparison will begin.
112 The offset is decimal by default, but may be expressed as a hexadecimal
113 or octal value by preceding it with a leading ``0x'' or ``0''.
118 may also be specified with SI size suffixes.
122 utility exits with one of the following values:
125 The files are identical.
127 The files are different; this includes the case
128 where one file is identical to the first part of
130 In the latter case, if the
132 option has not been specified,
134 writes to standard error that EOF was reached in the shorter
135 file (before any differences were found).
140 Assuming a file named
142 with the following contents:
143 .Bd -literal -offset indent
151 .Bd -literal -offset indent
152 $ echo -e "a\\nb\\nc" | cmp - example.txt
155 Same as above but introducing a change in the third byte of stdin.
156 Show the byte number (decimal) and differing byte (octal):
157 .Bd -literal -offset indent
158 $ echo -e "a\\nR\\nc" | cmp -l - example.txt
162 Compare file sizes of
165 .Pa /boot/loader.conf
166 and return 1 if they are not equal.
169 can only be used with regular files:
170 .Bd -literal -offset indent
171 $ cmp -z example.txt /boot/loader.conf
172 example.txt /boot/loader.conf differ: size
177 omitting the first 4 bytes from stdin and the first 2 bytes from
179 .Bd -literal -offset indent
180 $ echo -e "a\\nR\\nb\\nc" | cmp - example.txt 4 2
188 utility is expected to be
199 options are extensions to the standard.
203 arguments are extensions to the standard.
212 above refers to the traditional power of two convention, as described in
213 .Xr expand_number 3 .