WHAT(1) General Commands Manual WHAT(1)

what — identify SCCS files (DEVELOPMENT)


what [-s] file...

The what utility shall search the given files for all occurrences of the pattern that get(1) (see get(1)) substitutes for the % % keyword ( "@(#)"). The what utility shall write to standard output the identification string that follows up to, but not including, the first occurrence of one of the following: <double-quote> ( ‘"’ ), <greater-than-sign> ( ‘>’), <newline>, <backslash> ( ‘\\’), <NUL> ( ‘\0’), or an end-of-file condition on the input file. If not at end-of-file, the what utility shall then look for the next occurrence of "@(#)" after one of those characters.

The what utility shall conform to XBD V1_chap12(7).

The following option shall be supported:

Write at most one identification string for each file. After locating and writing to standard output the identification string following the first pattern (if any) in a file, no further data shall be read from that file and the search shall recommence from the beginning of the next file, if any.

The following operands shall be supported:

file
A pathname of a file to search.

Not used.

The input files shall be of any file type.

The following environment variables shall affect the execution of what:

Provide a default value for the internationalization variables that are unset or null. (See XBD for the precedence of internationalization variables used to determine the values of locale categories.)
If set to a non-empty string value, override the values of all the other internationalization variables.
Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments and input files).

Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
Determine the location of messages objects and message catalogs.

Default.

For each file operand, the standard output shall consist of:

"%s:\n", <pathname>

followed by zero or more of:

"\t%s\n", <identification string>

one for each identification string located.

The standard error shall be used only for diagnostic messages.

None.

None.

The following exit values shall be returned:

One or more matches were found and the output specified in STDOUT was successfully written to standard output.
No matches were found or an error occurred.

Default.

The what utility is intended to be used in conjunction with the SCCS command get(1), which automatically inserts identifying information, but it can also be used where the information is inserted by any other means.

When the string "@(#)" is included in a library routine in a shared library, it might not be found in an a.out file using that library routine.

If the C-language program in file f.c contains:

char ident[] = "@(#)identification information";

and f.c is compiled to yield and a.out, then the command:

what f.c f.o a.out

writes:

f.c:
    identification information
    ...
f.o:
    identification information
    ...
a.out:
    identification information
    ...

This standard requires that when the -s option is used, what does not continue reading from the current file after writing the first identification string. This might seem an unimportant detail, but applications would experience different behavior if a file operand named a FIFO special file and what waited for an end-of-file condition rather than closing the file straight away.

If this utility is directed to display a pathname that contains any bytes that have the encoded value of a <newline> character when <newline> is a terminator or separator in the output format being used, implementations are encouraged to treat this as an error. A future version of this standard may require implementations to treat this as an error.

get(1)

XBD V1_chap08(7), V1_chap12(7)

First released in Issue 2.

Austin Group Defect 251 is applied, encouraging implementations to report an error if a utility is directed to display a pathname that contains any bytes that have the encoded value of a <newline> character when <newline> is a terminator or separator in the output format being used.

Austin Group Defect 1122 is applied, changing the description of NLSPATH .

Austin Group Defect 1512 is applied, changing the EXIT STATUS section.

Austin Group Defect 1538 is applied, clarifying the -s option.

Austin Group Defect 1563 is applied, clarifying the output format when the what utility finds multiple identification strings in one file.

June 14, 2024 posix.fail