hash(1p)

1HASH(P)                    POSIX Programmer's Manual                   HASH(P)
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NAME

6       hash - remember or report utility locations
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SYNOPSIS

9       hash [utility...]
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11       hash -r
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DESCRIPTION

15       The  hash  utility  shall  affect the way the current shell environment
16       remembers the locations of utilities  found  as  described  in  Command
17       Search  and  Execution . Depending on the arguments specified, it shall
18       add utility locations to its list of remembered locations or  it  shall
19       purge  the  contents  of  the list. When no arguments are specified, it
20       shall report on the contents of the list.
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22       Utilities provided as built-ins to the shell shall not be  reported  by
23       hash.
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OPTIONS

26       The  hash  utility  shall  conform  to  the  Base Definitions volume of
27       IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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29       The following option shall be supported:
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31       -r     Forget all previously remembered utility locations.
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OPERANDS

35       The following operand shall be supported:
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37       utility
38              The name of a utility to be searched for and added to  the  list
39              of  remembered  locations.  If  utility  contains  one  or  more
40              slashes, the results are unspecified.
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STDIN

44       Not used.
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INPUT FILES

47       None.
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ENVIRONMENT VARIABLES

50       The following environment variables shall affect the execution of hash:
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52       LANG   Provide a default value for the  internationalization  variables
53              that  are  unset  or  null.  (See the Base Definitions volume of
54              IEEE Std 1003.1-2001, Section  8.2,  Internationalization  Vari‐
55              ables  for the precedence of internationalization variables used
56              to determine the values of locale categories.)
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58       LC_ALL If set to a non-empty string value, override the values  of  all
59              the other internationalization variables.
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61       LC_CTYPE
62              Determine  the  locale  for  the  interpretation of sequences of
63              bytes of text data as characters (for  example,  single-byte  as
64              opposed to multi-byte characters in arguments).
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66       LC_MESSAGES
67              Determine  the  locale  that should be used to affect the format
68              and contents of diagnostic messages written to standard error.
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70       NLSPATH
71              Determine the location of message catalogs for the processing of
72              LC_MESSAGES .
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74       PATH   Determine the location of utility, as described in the Base Def‐
75              initions volume of IEEE Std 1003.1-2001, Chapter 8,  Environment
76              Variables.
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ASYNCHRONOUS EVENTS

80       Default.
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STDOUT

83       The  standard output of hash shall be used when no arguments are speci‐
84       fied. Its format is unspecified, but  includes  the  pathname  of  each
85       utility in the list of remembered locations for the current shell envi‐
86       ronment. This list shall consist of those utilities named  in  previous
87       hash  invocations that have been invoked, and may contain those invoked
88       and found through the normal command search process.
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STDERR

91       The standard error shall be used only for diagnostic messages.
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OUTPUT FILES

94       None.
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EXTENDED DESCRIPTION

97       None.
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EXIT STATUS

100       The following exit values shall be returned:
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102        0     Successful completion.
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104       >0     An error occurred.
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CONSEQUENCES OF ERRORS

108       Default.
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110       The following sections are informative.
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APPLICATION USAGE

113       Since hash affects the  current  shell  execution  environment,  it  is
114       always provided as a shell regular built-in. If it is called in a sepa‐
115       rate utility execution environment, such as one of the following:
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118              nohup hash -r
119              find . -type f | xargs hash
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121       it does not affect the command search process of the caller's  environ‐
122       ment.
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124       The  hash  utility  may  be  implemented as an alias-for example, alias
125       -t -, in which case utilities found through normal command  search  are
126       not listed by the hash command.
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128       The  effects  of hash -r can also be achieved portably by resetting the
129       value of PATH ; in the simplest form, this can be:
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132              PATH="$PATH"
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134       The use of hash with utility names is  unnecessary  for  most  applica‐
135       tions,  but  may provide a performance improvement on a few implementa‐
136       tions; normally, the hashing process is included by default.
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EXAMPLES

139       None.
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RATIONALE

142       None.
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FUTURE DIRECTIONS

145       None.
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COPYRIGHT

151       Portions of this text are reprinted and reproduced in  electronic  form
152       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
153       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
154       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
155       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
156       event of any discrepancy between this version and the original IEEE and
157       The Open Group Standard, the original IEEE and The Open Group  Standard
158       is  the  referee document. The original Standard can be obtained online
159       at http://www.opengroup.org/unix/online.html .
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163IEEE/The Open Group                  2003                              HASH(P)