hash(1)

NAME
     hash - remember or report utility locations

SYNOPSIS
     hash [utility...]

     hash -r

DESCRIPTION
     The hash utility affects the way the current shell environment remembers
     the locations of utilities found as described in Command Search and
     Execution . Depending on the arguments specified, it adds utility
     locations to its list of remembered locations or it purges the contents
     of the list. When no arguments are specified, it reports on the contents
     of the list.

     Utilities provided as built-ins to the shell are not reported by hash.

OPTIONS
     The hash utility supports the XBD specification, Utility Syntax
     Guidelines.

     The following option is supported:

     -r  Forget all previously remembered utility locations.

OPERANDS
     The following operand is supported:

     utility   The name of a utility to be searched for and added to the list
               of remembered locations. If utility contains one or more
               slashes, the results are unspecified.

ENVIRONMENT VARIABLES
     The following environment variables affect the execution of hash:

     PATH   Determine the location of utility, as described in the XBD
            specification, Environment Variables .

STDOUT
     The standard output of hash is used when no arguments are specified.  Its
     format is unspecified, but includes the pathname of each utility in the
     list of remembered locations for the current shell environment.  This
     list consists of those utilities named in previous hash invocations that
     have been invoked, and may contain those invoked and found through the
     normal command search process.

EXIT STATUS
     The following exit values are returned:
     0   Successful completion.

     >0  An error occurred.

APPLICATION USAGE
     Since hash affects the current shell execution environment, it is always
     provided as a shell regular built-in. If it is called in a separate
     utility execution environment, such as one of the following:

          nohup hash -r find . -type f | xargs hash

     it will not affect the command search process of the caller's
     environment.

     The hash utility may be implemented as an alias, for example, alias -t -,
     in which case utilities found through normal command search will not be
     listed by the hash command.

     The effects of hash -r can also be achieved portably by resetting the
     value of PATH; in the simplest form, this can be:

          PATH="$PATH"

     The use of hash with utility names is unnecessary for most applications,
     but may provide a performance improvement on a few implementations;
     normally, the hashing process is included by default.

SEE ALSO
     sh(1)