mirror of https://github.com/mkerrisk/man-pages
185 lines
5.0 KiB
Groff
185 lines
5.0 KiB
Groff
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "HASH" 1P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" hash
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.SH NAME
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hash \- remember or report utility locations
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.SH SYNOPSIS
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.LP
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\fBhash\fP \fB[\fP\fIutility\fP\fB...\fP\fB]\fP\fB
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.br
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.sp
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hash -r \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIhash\fP utility shall affect the way the current shell environment
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remembers the locations of utilities found as
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described in \fICommand Search and Execution\fP . Depending on the
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arguments
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specified, it shall add utility locations to its list of remembered
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locations or it shall purge the contents of the list. When no
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arguments are specified, it shall report on the contents of the list.
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.LP
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Utilities provided as built-ins to the shell shall not be reported
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by \fIhash\fP.
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.SH OPTIONS
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.LP
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The \fIhash\fP utility shall conform to the Base Definitions volume
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of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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.LP
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The following option shall be supported:
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.TP 7
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\fB-r\fP
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Forget all previously remembered utility locations.
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.sp
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.SH OPERANDS
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.LP
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The following operand shall be supported:
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.TP 7
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\fIutility\fP
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The name of a utility to be searched for and added to the list of
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remembered locations. If \fIutility\fP contains one or more
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slashes, the results are unspecified.
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.sp
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.SH STDIN
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.LP
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Not used.
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.SH INPUT FILES
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.LP
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None.
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.SH ENVIRONMENT VARIABLES
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.LP
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The following environment variables shall affect the execution of
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\fIhash\fP:
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.TP 7
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\fILANG\fP
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Provide a default value for the internationalization variables that
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are unset or null. (See the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables
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for
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the precedence of internationalization variables used to determine
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the values of locale categories.)
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.TP 7
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\fILC_ALL\fP
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If set to a non-empty string value, override the values of all the
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other internationalization variables.
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.TP 7
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\fILC_CTYPE\fP
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Determine the locale for the interpretation of sequences of bytes
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of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).
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.TP 7
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\fILC_MESSAGES\fP
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Determine the locale that should be used to affect the format and
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contents of diagnostic messages written to standard
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error.
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.TP 7
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\fINLSPATH\fP
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Determine the location of message catalogs for the processing of \fILC_MESSAGES
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\&.\fP
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.TP 7
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\fIPATH\fP
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Determine the location of \fIutility\fP, as described in the Base
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Definitions volume of IEEE\ Std\ 1003.1-2001, Chapter 8, Environment
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Variables.
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.sp
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.SH ASYNCHRONOUS EVENTS
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.LP
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Default.
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.SH STDOUT
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.LP
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The standard output of \fIhash\fP shall be used when no arguments
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are specified. Its format is unspecified, but includes the
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pathname of each utility in the list of remembered locations for the
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current shell environment. This list shall consist of those
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utilities named in previous \fIhash\fP invocations that have been
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invoked, and may contain those invoked and found through the
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normal command search process.
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.SH STDERR
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.LP
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The standard error shall be used only for diagnostic messages.
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.SH OUTPUT FILES
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.LP
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None.
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.SH EXTENDED DESCRIPTION
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.LP
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None.
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.SH EXIT STATUS
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.LP
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The following exit values shall be returned:
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.TP 7
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\ 0
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Successful completion.
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.TP 7
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>0
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An error occurred.
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.sp
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.SH CONSEQUENCES OF ERRORS
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.LP
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Default.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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Since \fIhash\fP affects the current shell execution environment,
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it is always provided as a shell regular built-in. If it is
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called in a separate utility execution environment, such as one of
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the following:
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.sp
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.RS
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.nf
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\fBnohup hash -r
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find . -type f | xargs hash
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\fP
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.fi
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.RE
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.LP
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it does not affect the command search process of the caller's environment.
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.LP
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The \fIhash\fP utility may be implemented as an alias-for example,
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\fIalias\fP
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\fB-t\ -\fP, in which case utilities found through normal command
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search are not listed by the \fIhash\fP command.
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.LP
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The effects of \fIhash\fP \fB-r\fP can also be achieved portably by
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resetting the value of \fIPATH ;\fP in the simplest form,
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this can be:
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.sp
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.RS
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.nf
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\fBPATH="$PATH"
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\fP
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.fi
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.RE
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.LP
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The use of \fIhash\fP with \fIutility\fP names is unnecessary for
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most applications, but may provide a performance improvement
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on a few implementations; normally, the hashing process is included
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by default.
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.SH EXAMPLES
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.LP
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None.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fICommand Search and Execution\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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