hash [ -Ldfmrv ] [ name[=value] ] ...
       hash can be used to directly modify the contents of the  command
       hash  table,  and  the named directory hash table.  Normally one
       would modify these tables by modifying one's PATH (for the  com-
       mand  hash  table)  or  by creating appropriate shell parameters
       (for the named directory hash table).  The choice of hash  table
       to  work  on  is determined by the -d option; without the option
       the command hash table is used, and with the  option  the  named
       directory hash table is used.

       Given  no  arguments,  and  neither  the  -r  or -f options, the
       selected hash table will be listed in full.

       The -r option causes the selected hash table to be emptied.   It
       will  be  subsequently  rebuilt  in  the normal fashion.  The -f
       option causes the selected hash table to be fully rebuilt  imme-
       diately.   For  the command hash table this hashes all the abso-
       lute directories in the PATH, and for the named  directory  hash
       table  this adds all users' home directories.  These two options
       cannot be used with any arguments.

       The -m option causes the  arguments  to  be  taken  as  patterns
       (which  should  be  quoted)  and  the elements of the hash table
       matching those patterns are printed.  This is the  only  way  to
       display a limited selection of hash table elements.

       For  each  name  with  a  corresponding value, put `name' in the
       selected hash table, associating it with the  pathname  `value'.
       In  the  command  hash table, this means that whenever `name' is
       used as a command argument, the shell will try  to  execute  the
       file  given by `value'.  In the named directory hash table, this
       means that `value' may be referred to as `~name'.

       For each name with no corresponding value, attempt to  add  name
       to the hash table, checking what the appropriate value is in the
       normal manner for that hash  table.   If  an  appropriate  value
       can't be found, then the hash table will be unchanged.

       The -v option causes hash table entries to be listed as they are
       added by explicit specification.  If has no effect if used  with
       -f.

       If the -L flag is present, then each hash table entry is printed
       in the form of a call to hash.

rehash Same as hash -r.