REHASH(1CSH)            COMMAND REFERENCE            REHASH(1CSH)



NAME
     rehash, unhash, hashstat - hashing control and report
     commands (csh built-in)

SYNOPSIS
     rehash
     unhash
     hashstat

DESCRIPTION
     In order to speed up execution path searching, csh(1csh)
     hashes the commands in each of the directories in the
     execution path.  When executing a command, the command name
     is hashed to see if it could possibly be in a given
     directory.  If the hash value of the command name indicates
     that the command may be in a given directory, csh attempts
     to execute that command.  If the execution succeeds, the
     operation is called a hit. If not, the operation is called a
     miss.

     The command rehash causes the internal hash table to be
     recomputed.  This is usually required when new commands are
     added to directories in the execution path.

     The command unhash disables execution path hashing.  This is
     useful when a lot of changes are being made to the
     directories in the execution path.

     The command hashstat prints a short report about the
     efficiency of the hashing.  The report is of the form:
     number hits, number misses, number %.  The hits and misses
     numbers correspond to the number of hits and misses (as
     explained above) since the shell was invoked.  The
     percentage given is the percentage of the total attempts
     that succeeded in a hit.

EXAMPLES
     In order to cause the internal command hash table to be
     recomputed, execute the command:

          rehash

RETURN VALUE
     [NO_ERRS]      Command completed without error.

CAVEATS
     The more commands that exist in a given directory, the more
     times the hashing result in a miss.

     The hashing in csh is quite different from sh(1sh) hashing,
     in that the latter stores information on a command when it
     is executed and is more efficient when a directory contains



Printed 4/6/89                                                  1

REHASH(1CSH)            COMMAND REFERENCE            REHASH(1CSH)



     a lot of commands.

SEE ALSO
     @(1csh), alias(1csh), bg(1csh), break(1csh), cd(1csh),
     chdir(1csh), continue(1csh), csh(1csh), dirs(1csh),
     echo(1csh), eval(1csh), exec(1csh), exit(1csh), fg(1csh),
     glob(1csh), goto(1csh), hash(1sh), history(1csh),
     jobs(1csh), kill(1csh), limit(1csh), logout(1csh),
     nice(1csh), nohup(1csh), notify(1csh), onintr(1csh),
     popd(1csh), pushd(1csh), repeat(1csh), set(1csh),
     setenv(1csh), sh(1sh), shift(1csh), source(1csh),
     stop(1csh), suspend(1csh), time(1csh), umask(1csh),
     unalias(1csh), unlimit(1csh), unset(1csh), unsetenv(1csh),
     wait(1csh), which(1csh), and execve(2).









































Printed 4/6/89                                                  2

%%index%%
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sy:524,328;
de:852,1769;
ex:2621,207;
rv:2828,177;
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%%index%%000000000131