8.4.4 cmp command (compares binary files)

Syntax

cmp [-l|-s] path-name-1 path-name-2 [skip-1 [skip-2]]

Description

This command compares binary files. Differences in byte values and the locations where the differences occur can be displayed.

Arguments

If the -l and -s options are both omitted, the command displays only the location where the first difference is detected. An error results if the -l and -s options are both specified.

-l: Specifies that each set of a difference in byte values (octal) and their offset in bytes (decimal) are to be displayed.
-s: Specifies that only a termination status indicating whether the files are different is to be returned.
path-name-1: Specifies the path name of the comparison source file. If you specify - for path-name-1, the contents for comparison are read from the standard input.
path-name-2: Specifies the path name of the comparison target file. If you specify - for path-name-2, the contents for comparison are read from the standard input.
skip-1: Specifies the position (in bytes) in the file in path-name-1 that is to be the beginning point of the comparison processing.
skip-2: Specifies the position (in bytes) in the file in path-name-2 that is to be the beginning point of the comparison processing.

Return codes

Return code	Meaning
`0`	Normal termination. The files are identical.
`1`	Normal termination. The files are different. Or, the end-of-file (`EOF`) was reached earlier in one file than in the other, in which case a message (`cmp: EOF on` `file-name`) is output.
`2` or greater	Error termination

Notes

The end-of-line code [CR] + [LF] is considered two bytes.
In Windows, input from a file or from the standard input is performed in binary mode. No conversion of end-of-line codes is performed.

Examples

These usage examples illustrate the results of executing the cmp command on the files abc.txt and abcd.txt, whose contents are shown below. In the examples, [Figure] represents a space and represents a tab character.

abc.txt

aaaaaaaaaaa
 
bbbbbbbb


cccccccccccccccc

               


dddddddddddd

abcd.txt

aaaaaaaaaaa
 
bbbbbbbb


cccccccccccccccc




dddddddddddd
eeeeeeeeeeeeeeeee

The files listed above are the input files in the following examples, which illustrate the results of executing the cmp command.

Specify the -l option to display the offset in bytes (decimal) and the values (octal) of each difference between abc.txt and abcd.txt.

C:\TEMP>%ADSH_OSCMD_DIR%\cmp -l abc.txt abcd.txt
    49  12  40
    50  11  40
    51  11  40
    52  11  40
    53  12  40
    54  12  40
    65  40  12
    66  12  40
    67 144  40
    68 144  40
    69 144  40
    70 144  40
    71 144  40
    72 144  40
    73 144  40
    74 144  40
    75 144  40
    76 144  40
    77 144  40
    78 144  40
    79  12  40
cmp: EOF on abc.txt

Specify the -s option to return the return code without displaying the results.
```
C:\TEMP>%ADSH_OSCMD_DIR%\cmp -s abc.txt abcd.txt
```
Specify the optional skip arguments to set the starting bytes for comparison to 3 for each file. In the first example, the skip arguments are omitted. In the second example, they are set to 3.
```
C:\TEMP>%ADSH_OSCMD_DIR%\cmp abc.txt  abcd.txt
abc.txt abcd.txt differ: char 49, line 7
 
C:\TEMP>%ADSH_OSCMD_DIR%\cmp abc.txt  abcd.txt  3 3
abc.txt abcd.txt differ: char 46, line 7
```
Display an option error message.

This message might vary depending on the platform on which the command is executed. The following shows an example in Windows:
```
C:\TEMP>%ADSH_OSCMD_DIR%\cmp -w
cmp: illegal option -- w
usage: cmp [-l | -s] file1 file2 [skip1 [skip2]]
```

Display an error message if the file does not exist:

C:\TEMP>%ADSH_OSCMD_DIR%\cmp file99 file123
cmp: file99: No such file or directory

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