WHICH

Section: User Commands (1)
Updated: 28 Jul 93 (v2.1)
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NAME

which - locate commands and data files, and print paths

SYNOPSIS

which [ -a ] [ -l | -d ] command [ command ... ]

ARGUMENTS

command: Command or list of commands (or files) to locate.

OPTIONS

-a: list all matches, not just first one
-l: search LIBPATH for DLLs
-d: search DPATH for data files

DESCRIPTION

By default which checks, in order, command-shell aliases (4DOS and 4OS2 only), internal command-shell commands, the current directory, and directories specified in the user's PATH variable for the commands given as its arguments. If a given command is found, its full path is printed; otherwise a ``not found'' message is printed with a list of the directories which were checked. In the case the command is an internal shell command, a message to this effect is printed in lieu of a path.

which respects the shell precedence of command extensions; thus more.com is listed instead of more.exe, should both exist in the same directory. Likewise, .exe files have precedence over .cmd files, and .cmd files over .bat files. A command with a dot in its name has precedence over any default extension; for example, list.old is found before list.old.exe.

The -a option causes which to list all matching commands in the path, not just the one which would be executed. The -d and -l options alter the nature of the search; when -d is specified, which searches directories in the DPATH for data files, and when -l is specified, it searches through the LIBPATH for dynamic link libraries (.DLLs). The -d and -l options are mutually exclusive, and in both cases the current directory is searched only if ``.'' is listed in the appropriate path.

EXAMPLES

To find the locations of five commands:

which dir pushd format unzip zipinfo

The output might look something like the following:

dir: 4OS2.EXE internal command
pushd: aliased to c:\utils\16\pushd.cmd
c:\os2\format.com
c:\utils\32\unzip.exe
no zipinfo in c:\os2 . c:\utils\32 c:\utils\16
c:\utils\bnd c:\os2\system c:\emx\bin
c:\groff\bin c:\os2\mdos\winos2 c:\os2\install
c:\ c:\os2\mdos c:\os2\apps c:\ibmtk\os2bin
c:\ibmwf\bin c:\ibmc\bin

To locate all copies of the emx.dll dynamic link library (the first one listed is the one which will be used by the operating system):

which -al emx

To find two of the IBM Redbooks (.inf format):

which -d gg243732 gg243774

BUGS

For CMD.EXE and COMMAND.COM, the list of internal shell commands is static and does not reflect differences between various versions of the command shell. The current command lists correspond roughly to OS/2 2.0 and MS-DOS 5.0.

MS-DOS 5.0 and 6.0 DOSKEY aliases (``macros'') are not yet detected, because there's no good way to do so without writing a temporary file.

There is no reasonable way to determine the LIBPATH in a foolproof manner; it does not have a corresponding environment variable or system call. which looks in the config.sys system file for LIBPATH, but this can fail if the LIBPATH line has been edited since the system was last booted. In addition, under OS/2 1.x there is no way to determine the boot drive, so which may fail even to find the proper config.sys. The 16-bit (or bound) executable first checks for \config.sys on the current drive and then on drive c:, but this will fail if, for example, the system was booted from floppy drive a: and the current drive is c:. The 32-bit executable can determine the boot drive but is still susceptible to editing changes and the possible removal of the boot floppy.

The list of ``proper'' extensions for use with DPATH is somewhat hazy; the following are presently used: .boo, .dat, .hlp, .inf, .ini, .msg and .ndx.

AUTHOR

Greg Roelofs (also known as Cave Newt). The makefile was liberally borrowed from Kai Uwe Rommel's UnZip makefile.os2. Michael Lawler and Kenneth Porter contributed code as noted in the source file.

This document was created by man2html, using the manual pages.
Time: 04:04:48 GMT, November 11, 2022