mirror of https://github.com/mkerrisk/man-pages
1359 lines
53 KiB
Groff
1359 lines
53 KiB
Groff
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "SH" 1P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" sh
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.SH NAME
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sh \- shell, the standard command language interpreter
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.SH SYNOPSIS
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.LP
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\fBsh\fP \fB[\fP\fB-abCefhimnuvx\fP\fB][\fP\fB-o\fP \fIoption\fP\fB][\fP\fB+abCefhimnuvx\fP\fB][\fP\fB+o\fP
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\fIoption\fP\fB]
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.br
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\fP \fB\ \ \ \ \ \ \fP \fB[\fP\fIcommand_file\fP \fB[\fP\fIargument\fP\fB...\fP\fB]]\fP\fB
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.br
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.sp
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sh -c\fP\fB[\fP\fB-abCefhimnuvx\fP\fB][\fP\fB-o\fP \fIoption\fP\fB][\fP\fB+abCefhimnuvx\fP\fB][\fP\fB+o\fP
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\fIoption\fP\fB]\fP\fIcommand_string
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.br
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\fP \fB\ \ \ \ \ \ \fP \fI\fP\fB[\fP\fIcommand_name\fP
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\fB[\fP\fIargument\fP\fB...\fP\fB]]\fP\fB
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.br
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.sp
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sh -s\fP\fB[\fP\fB-abCefhimnuvx\fP\fB][\fP\fB-o\fP \fIoption\fP\fB][\fP\fB+abCefhimnuvx\fP\fB][\fP\fB+o\fP
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\fIoption\fP\fB][\fP\fIargument\fP\fB]\fP\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 \fIsh\fP utility is a command language interpreter that shall
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execute commands read from a command line string, the
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standard input, or a specified file. The application shall ensure
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that the commands to be executed are expressed in the language
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described in \fIShell Command Language\fP .
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.LP
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Pathname expansion shall not fail due to the size of a file.
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.LP
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Shell input and output redirections have an implementation-defined
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offset maximum that is established in the open file
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description.
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.SH OPTIONS
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.LP
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The \fIsh\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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with an extension for support of a leading
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plus sign ( \fB'+'\fP ) as noted below.
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.LP
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The \fB-a\fP, \fB-b\fP, \fB-C\fP, \fB-e\fP, \fB-f\fP, \fB-m\fP, \fB-n\fP,
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\fB-o\fP \fIoption\fP, \fB-u\fP, \fB-v\fP,
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and \fB-x\fP options are described as part of the \fIset\fP utility
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in \fISpecial Built-In Utilities\fP . The option letters derived from
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the \fIset\fP special built-in shall also be accepted with a leading
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plus sign ( \fB'+'\fP )
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instead of a leading hyphen (meaning the reverse case of the option
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as described in this volume of
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IEEE\ Std\ 1003.1-2001).
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.LP
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The following additional options shall be supported:
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.TP 7
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\fB-c\fP
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Read commands from the \fIcommand_string\fP operand. Set the value
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of special parameter 0 (see \fISpecial Parameters\fP ) from the value
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of the \fIcommand_name\fP operand and the positional
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parameters ($1, $2, and so on) in sequence from the remaining \fIargument\fP
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operands. No commands shall be read from the standard
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input.
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.TP 7
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\fB-i\fP
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Specify that the shell is \fIinteractive\fP; see below. An implementation
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may treat specifying the \fB-i\fP option as an
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error if the real user ID of the calling process does not equal the
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effective user ID or if the real group ID does not equal the
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effective group ID.
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.TP 7
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\fB-s\fP
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Read commands from the standard input.
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.sp
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.LP
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If there are no operands and the \fB-c\fP option is not specified,
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the \fB-s\fP option shall be assumed.
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.LP
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If the \fB-i\fP option is present, or if there are no operands and
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the shell's standard input and standard error are attached
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to a terminal, the shell is considered to be \fIinteractive\fP.
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.SH OPERANDS
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.LP
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The following operands shall be supported:
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.TP 7
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\fB-\fP
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A single hyphen shall be treated as the first operand and then ignored.
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If both \fB'-'\fP and \fB"--"\fP are given as
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arguments, or if other operands precede the single hyphen, the results
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are undefined.
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.TP 7
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\fIargument\fP
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The positional parameters ($1, $2, and so on) shall be set to \fIarguments\fP,
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if any.
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.TP 7
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\fIcommand_file\fP
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The pathname of a file containing commands. If the pathname contains
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one or more slash characters, the implementation attempts
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to read that file; the file need not be executable. If the pathname
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does not contain a slash character:
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.RS
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.IP " *" 3
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The implementation shall attempt to read that file from the current
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working directory; the file need not be executable.
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.LP
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.IP " *" 3
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If the file is not in the current working directory, the implementation
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may perform a search for an executable file using the
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value of \fIPATH ,\fP as described in \fICommand Search and Execution\fP
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\&.
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.LP
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.RE
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.LP
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Special parameter 0 (see \fISpecial Parameters\fP ) shall be set to
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the value of
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\fIcommand_file\fP. If \fIsh\fP is called using a synopsis form that
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omits \fIcommand_file\fP, special parameter 0 shall be set
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to the value of the first argument passed to \fIsh\fP from its parent
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(for example, \fIargv\fP[0] for a C program), which is
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normally a pathname used to execute the \fIsh\fP utility.
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.TP 7
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\fIcommand_name\fP
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.sp
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A string assigned to special parameter 0 when executing the commands
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in \fIcommand_string\fP. If \fIcommand_name\fP is not
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specified, special parameter 0 shall be set to the value of the first
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argument passed to \fIsh\fP from its parent (for example,
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\fIargv\fP[0] for a C program), which is normally a pathname used
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to execute the \fIsh\fP utility.
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.TP 7
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\fIcommand_string\fP
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.sp
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A string that shall be interpreted by the shell as one or more commands,
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as if the string were the argument to the \fIsystem\fP() function
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defined in the System Interfaces volume of IEEE\ Std\ 1003.1-2001.
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If the \fIcommand_string\fP operand is an empty string, \fIsh\fP shall
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exit with a zero exit status.
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.sp
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.SH STDIN
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.LP
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The standard input shall be used only if one of the following is true:
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.IP " *" 3
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The \fB-s\fP option is specified.
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.LP
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.IP " *" 3
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The \fB-c\fP option is not specified and no operands are specified.
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.LP
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.IP " *" 3
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The script executes one or more commands that require input from standard
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input (such as a \fIread\fP command that does not redirect its input).
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.LP
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.LP
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See the INPUT FILES section.
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.LP
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When the shell is using standard input and it invokes a command that
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also uses standard input, the shell shall ensure that the
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standard input file pointer points directly after the command it has
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read when the command begins execution. It shall not read
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ahead in such a manner that any characters intended to be read by
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the invoked command are consumed by the shell (whether
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interpreted by the shell or not) or that characters that are not read
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by the invoked command are not seen by the shell. When the
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command expecting to read standard input is started asynchronously
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by an interactive shell, it is unspecified whether characters
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are read by the command or interpreted by the shell.
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.LP
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If the standard input to \fIsh\fP is a FIFO or terminal device and
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is set to non-blocking reads, then \fIsh\fP shall enable
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blocking reads on standard input. This shall remain in effect when
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the command completes.
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.SH INPUT FILES
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.LP
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The input file shall be a text file, except that line lengths shall
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be unlimited. If the input file is empty or consists solely
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of blank lines or comments, or both, \fIsh\fP shall exit with a zero
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exit status.
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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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\fIsh\fP:
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.TP 7
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\fIENV\fP
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This variable, when and only when an interactive shell is invoked,
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shall be subjected to parameter expansion (see \fIParameter Expansion\fP
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) by the shell, and the resulting value shall be used as a pathname
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of a file containing shell commands to execute in the current environment.
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The file need not be executable. If the expanded value
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of \fIENV\fP is not an absolute pathname, the results are unspecified.
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\fIENV\fP shall be ignored if the real and effective user
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IDs or real and effective group IDs of the process are different.
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.TP 7
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\fIFCEDIT\fP
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This variable, when expanded by the shell, shall determine the default
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value for the \fB-e\fP \fIeditor\fP option's
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\fIeditor\fP option-argument. If \fIFCEDIT\fP is null or unset, \fIed\fP
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shall be used as the
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editor. This volume of IEEE\ Std\ 1003.1-2001 specifies the effects
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of this variable only for systems supporting the User
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Portability Utilities option.
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.TP 7
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\fIHISTFILE\fP
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Determine a pathname naming a command history file. If the \fIHISTFILE\fP
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variable is not set, the shell may attempt to access
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or create a file \fB.sh_history\fP in the directory referred to by
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the \fIHOME\fP environment variable. If the shell cannot
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obtain both read and write access to, or create, the history file,
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it shall use an unspecified mechanism that allows the history to
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operate properly. (References to history "file" in this section shall
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be understood to mean this unspecified mechanism in such
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cases.) An implementation may choose to access this variable only
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when initializing the history file; this initialization shall
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occur when \fIfc\fP or \fIsh\fP first attempt to retrieve entries
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from, or add entries to, the
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file, as the result of commands issued by the user, the file named
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by the \fIENV\fP variable, or implementation-defined system
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start-up files. Implementations may choose to disable the history
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list mechanism for users with appropriate privileges who do not
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set \fIHISTFILE ;\fP the specific circumstances under which this occurs
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are implementation-defined. If more than one instance of
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the shell is using the same history file, it is unspecified how updates
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to the history file from those shells interact. As entries
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are deleted from the history file, they shall be deleted oldest first.
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It is unspecified when history file entries are physically
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removed from the history file. This volume of IEEE\ Std\ 1003.1-2001
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specifies the effects of this variable only for
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systems supporting the User Portability Utilities option.
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.TP 7
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\fIHISTSIZE\fP
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Determine a decimal number representing the limit to the number of
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previous commands that are accessible. If this variable is
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unset, an unspecified default greater than or equal to 128 shall be
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used. The maximum number of commands in the history list is
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unspecified, but shall be at least 128. An implementation may choose
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to access this variable only when initializing the history
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file, as described under \fIHISTFILE .\fP Therefore, it is unspecified
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whether changes made to \fIHISTSIZE\fP after the history
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file has been initialized are effective.
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.TP 7
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\fIHOME\fP
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Determine the pathname of the user's home directory. The contents
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of \fIHOME\fP are used in tilde expansion as described in \fITilde
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Expansion\fP . This volume of IEEE\ Std\ 1003.1-2001 specifies the
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effects of this variable only for systems supporting the User Portability
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Utilities option.
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.TP 7
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\fIIFS\fP
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(Input Field Separators.) A string treated as a list of characters
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that shall be used for field splitting and to split lines
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into words with the \fIread\fP command. See \fIField
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Splitting\fP . If \fIIFS\fP is not set, the shell shall behave as
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if the value of \fIIFS\fP were <space>, <tab>,
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and <newline>. Implementations may ignore the value of \fIIFS\fP in
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the environment at the time \fIsh\fP is invoked,
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treating \fIIFS\fP as if it were not set.
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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_COLLATE\fP
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.sp
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Determine the behavior of range expressions, equivalence classes,
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and multi-character collating elements within pattern
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matching.
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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 and input files), which
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characters are defined as letters (character class
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\fBalpha\fP), and the behavior of character classes within pattern
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matching.
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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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\fIMAIL\fP
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Determine a pathname of the user's mailbox file for purposes of incoming
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mail notification. If this variable is set, the shell
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shall inform the user if the file named by the variable is created
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or if its modification time has changed. Informing the user
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shall be accomplished by writing a string of unspecified format to
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standard error prior to the writing of the next primary prompt
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string. Such check shall be performed only after the completion of
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the interval defined by the \fIMAILCHECK\fP variable after the
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last such check. The user shall be informed only if \fIMAIL\fP is
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set and \fIMAILPATH\fP is not set. This volume of
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IEEE\ Std\ 1003.1-2001 specifies the effects of this variable only
|
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for systems supporting the User Portability Utilities
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option.
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.TP 7
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\fIMAILCHECK\fP
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.sp
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Establish a decimal integer value that specifies how often (in seconds)
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the shell shall check for the arrival of mail in the files
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specified by the \fIMAILPATH\fP or \fIMAIL\fP variables. The default
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value shall be 600 seconds. If set to zero, the shell shall
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check before issuing each primary prompt. This volume of IEEE\ Std\ 1003.1-2001
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specifies the effects of this variable only
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for systems supporting the User Portability Utilities option.
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.TP 7
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\fIMAILPATH\fP
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Provide a list of pathnames and optional messages separated by colons.
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If this variable is set, the shell shall inform the user
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if any of the files named by the variable are created or if any of
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their modification times change. (See the preceding entry for
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\fIMAIL\fP for descriptions of mail arrival and user informing.) Each
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pathname can be followed by \fB'%'\fP and a string that
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shall be subjected to parameter expansion and written to standard
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|
error when the modification time changes. If a \fB'%'\fP
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|
character in the pathname is preceded by a backslash, it shall be
|
|
treated as a literal \fB'%'\fP in the pathname. The default
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|
message is unspecified.
|
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.LP
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The \fIMAILPATH\fP environment variable takes precedence over the
|
|
\fIMAIL\fP variable. This volume of
|
|
IEEE\ Std\ 1003.1-2001 specifies the effects of this variable only
|
|
for systems supporting the User Portability Utilities
|
|
option.
|
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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
|
|
.TP 7
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|
\fIPATH\fP
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Establish a string formatted as described in the Base Definitions
|
|
volume of IEEE\ Std\ 1003.1-2001, Chapter 8, Environment Variables,
|
|
used to effect command interpretation; see \fICommand Search and Execution\fP
|
|
\&.
|
|
.TP 7
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|
\fIPWD\fP
|
|
This variable shall represent an absolute pathname of the current
|
|
working directory. Assignments to this variable may be
|
|
ignored unless the value is an absolute pathname of the current working
|
|
directory and there are no filename components of dot or
|
|
dot-dot.
|
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.sp
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.SH ASYNCHRONOUS EVENTS
|
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.LP
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|
Default.
|
|
.SH STDOUT
|
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.LP
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|
See the STDERR section.
|
|
.SH STDERR
|
|
.LP
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|
Except as otherwise stated (by the descriptions of any invoked utilities
|
|
or in interactive mode), standard error shall be used
|
|
only for diagnostic messages.
|
|
.SH OUTPUT FILES
|
|
.LP
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|
None.
|
|
.SH EXTENDED DESCRIPTION
|
|
.LP
|
|
See \fIShell Command Language\fP . The following additional capabilities
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|
are supported on
|
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systems supporting the User Portability Utilities option.
|
|
.SS Command History List
|
|
.LP
|
|
When the \fIsh\fP utility is being used interactively, it shall maintain
|
|
a list of commands previously entered from the
|
|
terminal in the file named by the \fIHISTFILE\fP environment variable.
|
|
The type, size, and internal format of this file are
|
|
unspecified. Multiple \fIsh\fP processes can share access to the file
|
|
for a user, if file access permissions allow this; see the
|
|
description of the \fIHISTFILE\fP environment variable.
|
|
.SS Command Line Editing
|
|
.LP
|
|
When \fIsh\fP is being used interactively from a terminal, the current
|
|
command and the command history (see \fIfc\fP ) can be edited using
|
|
\fIvi\fP-mode command line editing. This mode
|
|
uses commands, described below, similar to a subset of those described
|
|
in the \fIvi\fP utility.
|
|
Implementations may offer other command line editing modes corresponding
|
|
to other editing utilities.
|
|
.LP
|
|
The command \fIset\fP \fB-o\fP \fIvi\fP
|
|
shall enable \fIvi\fP-mode editing and place \fIsh\fP into \fIvi\fP
|
|
insert mode (see Command Line Editing (vi-mode) ). This
|
|
command also shall disable any other editing mode that the implementation
|
|
may provide. The command \fIset\fP \fB+o\fP \fIvi\fP disables \fIvi\fP-mode
|
|
editing.
|
|
.LP
|
|
Certain block-mode terminals may be unable to support shell command
|
|
line editing. If a terminal is unable to provide either edit
|
|
mode, it need not be possible to \fIset\fP \fB-o\fP \fIvi\fP when
|
|
using the shell on this terminal.
|
|
.LP
|
|
In the following sections, the characters \fIerase\fP, \fIinterrupt\fP,
|
|
\fIkill\fP, and \fIend-of-file\fP are those set by
|
|
the \fIstty\fP utility.
|
|
.SS Command Line Editing (vi-mode)
|
|
.LP
|
|
In \fIvi\fP editing mode, there shall be a distinguished line, the
|
|
edit line. All the
|
|
editing operations which modify a line affect the edit line. The edit
|
|
line is always the newest line in the command history
|
|
buffer.
|
|
.LP
|
|
With \fIvi\fP-mode enabled, \fIsh\fP can be switched between insert
|
|
mode and command
|
|
mode.
|
|
.LP
|
|
When in insert mode, an entered character shall be inserted into the
|
|
command line, except as noted in vi Line Editing Insert Mode . Upon
|
|
entering \fIsh\fP and after termination of the previous command,
|
|
\fIsh\fP shall be in insert mode.
|
|
.LP
|
|
Typing an escape character shall switch \fIsh\fP into command mode
|
|
(see vi Line Editing Command
|
|
Mode ). In command mode, an entered character shall either invoke
|
|
a defined operation, be used as part of a multi-character
|
|
operation, or be treated as an error. A character that is not recognized
|
|
as part of an editing command shall terminate any specific
|
|
editing command and shall alert the terminal. Typing the \fIinterrupt\fP
|
|
character in command mode shall cause \fIsh\fP to
|
|
terminate command line editing on the current command line, reissue
|
|
the prompt on the next line of the terminal, and reset the
|
|
command history (see \fIfc\fP ) so that the most recently executed
|
|
command is the previous command (that is,
|
|
the command that was being edited when it was interrupted is not reentered
|
|
into the history).
|
|
.LP
|
|
In the following sections, the phrase "move the cursor to the beginning
|
|
of the word" shall mean "move the cursor to the first
|
|
character of the current word" and the phrase "move the cursor to
|
|
the end of the word" shall mean "move the cursor to the last
|
|
character of the current word". The phrase "beginning of the command
|
|
line" indicates the point between the end of the prompt
|
|
string issued by the shell (or the beginning of the terminal line,
|
|
if there is no prompt string) and the first character of the
|
|
command text.
|
|
.SS vi Line Editing Insert Mode
|
|
.LP
|
|
While in insert mode, any character typed shall be inserted in the
|
|
current command line, unless it is from the following
|
|
set.
|
|
.TP 7
|
|
<newline>
|
|
Execute the current command line. If the current command line is not
|
|
empty, this line shall be entered into the command history
|
|
(see \fIfc\fP ).
|
|
.TP 7
|
|
\fIerase\fP
|
|
Delete the character previous to the current cursor position and move
|
|
the current cursor position back one character. In insert
|
|
mode, characters shall be erased from both the screen and the buffer
|
|
when backspacing.
|
|
.TP 7
|
|
\fIinterrupt\fP
|
|
Terminate command line editing with the same effects as described
|
|
for interrupting command mode; see Command Line Editing (vi-mode)
|
|
\&.
|
|
.TP 7
|
|
\fIkill\fP
|
|
Clear all the characters from the input line.
|
|
.TP 7
|
|
<control>-V
|
|
Insert the next character input, even if the character is otherwise
|
|
a special insert mode character.
|
|
.TP 7
|
|
<control>-W
|
|
Delete the characters from the one preceding the cursor to the preceding
|
|
word boundary. The word boundary in this case is the
|
|
closer to the cursor of either the beginning of the line or a character
|
|
that is in neither the \fBblank\fP nor \fBpunct\fP
|
|
character classification of the current locale.
|
|
.TP 7
|
|
\fIend-of-file\fP
|
|
Interpreted as the end of input in \fIsh\fP. This interpretation shall
|
|
occur only at the beginning of an input line. If
|
|
\fIend-of-file\fP is entered other than at the beginning of the line,
|
|
the results are unspecified.
|
|
.TP 7
|
|
<ESC>
|
|
Place \fIsh\fP into command mode.
|
|
.sp
|
|
.SS vi Line Editing Command Mode
|
|
.LP
|
|
In command mode for the command line editing feature, decimal digits
|
|
not beginning with 0 that precede a command letter shall be
|
|
remembered. Some commands use these decimal digits as a count number
|
|
that affects the operation.
|
|
.LP
|
|
The term \fImotion command\fP represents one of the commands:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB<space> 0 b F l W ^ $ ; E f T w | , B e h t
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
If the current line is not the edit line, any command that modifies
|
|
the current line shall cause the content of the current line
|
|
to replace the content of the edit line, and the current line shall
|
|
become the edit line. This replacement cannot be undone (see
|
|
the \fBu\fP and \fBU\fP commands below). The modification requested
|
|
shall then be performed to the edit line. When the current
|
|
line is the edit line, the modification shall be done directly to
|
|
the edit line.
|
|
.LP
|
|
Any command that is preceded by \fIcount\fP shall take a count (the
|
|
numeric value of any preceding decimal digits). Unless
|
|
otherwise noted, this count shall cause the specified operation to
|
|
repeat by the number of times specified by the count. Also
|
|
unless otherwise noted, a \fIcount\fP that is out of range is considered
|
|
an error condition and shall alert the terminal, but
|
|
neither the cursor position, nor the command line, shall change.
|
|
.LP
|
|
The terms \fIword\fP and \fIbigword\fP are used as defined in the
|
|
\fIvi\fP description.
|
|
The term \fIsave buffer\fP corresponds to the term \fIunnamed buffer\fP
|
|
in \fIvi\fP.
|
|
.LP
|
|
The following commands shall be recognized in command mode:
|
|
.TP 7
|
|
<newline>
|
|
Execute the current command line. If the current command line is not
|
|
empty, this line shall be entered into the command history
|
|
(see \fIfc\fP ).
|
|
.TP 7
|
|
<control>-L
|
|
Redraw the current command line. Position the cursor at the same location
|
|
on the redrawn line.
|
|
.TP 7
|
|
\fB#\fP
|
|
Insert the character \fB'#'\fP at the beginning of the current command
|
|
line and treat the resulting edit line as a comment.
|
|
This line shall be entered into the command history; see \fIfc\fP
|
|
\&.
|
|
.TP 7
|
|
\fB=\fP
|
|
Display the possible shell word expansions (see \fIWord Expansions\fP
|
|
) of the bigword
|
|
at the current command line position.
|
|
.TP 7
|
|
\fBNote:\fP
|
|
.RS
|
|
This does not modify the content of the current line, and therefore
|
|
does not cause the current line to become the edit
|
|
line.
|
|
.RE
|
|
.sp
|
|
.LP
|
|
These expansions shall be displayed on subsequent terminal lines.
|
|
If the bigword contains none of the characters \fB'?'\fP ,
|
|
\fB'*'\fP , or \fB'['\fP , an asterisk ( \fB'*'\fP ) shall be implicitly
|
|
assumed at the end. If any directories are
|
|
matched, these expansions shall have a \fB'/'\fP character appended.
|
|
After the expansion, the line shall be redrawn, the cursor
|
|
repositioned at the current cursor position, and \fIsh\fP shall be
|
|
placed in command mode.
|
|
.TP 7
|
|
\fB\\\fP
|
|
Perform pathname expansion (see \fIPathname Expansion\fP ) on the
|
|
current bigword,
|
|
up to the largest set of characters that can be matched uniquely.
|
|
If the bigword contains none of the characters \fB'?'\fP ,
|
|
\fB'*'\fP , or \fB'['\fP , an asterisk ( \fB'*'\fP ) shall be implicitly
|
|
assumed at the end. This maximal expansion then
|
|
shall replace the original bigword in the command line, and the cursor
|
|
shall be placed after this expansion. If the resulting
|
|
bigword completely and uniquely matches a directory, a \fB'/'\fP character
|
|
shall be inserted directly after the bigword. If some
|
|
other file is completely matched, a single <space> shall be inserted
|
|
after the bigword. After this operation, \fIsh\fP shall
|
|
be placed in insert mode.
|
|
.TP 7
|
|
\fB*\fP
|
|
Perform pathname expansion on the current bigword and insert all expansions
|
|
into the command to replace the current bigword,
|
|
with each expansion separated by a single <space>. If at the end of
|
|
the line, the current cursor position shall be moved to
|
|
the first column position following the expansions and \fIsh\fP shall
|
|
be placed in insert mode. Otherwise, the current cursor
|
|
position shall be the last column position of the first character
|
|
after the expansions and \fIsh\fP shall be placed in insert
|
|
mode. If the current bigword contains none of the characters \fB'?'\fP
|
|
, \fB'*'\fP , or \fB'['\fP , before the operation,
|
|
an asterisk shall be implicitly assumed at the end.
|
|
.TP 7
|
|
\fB@\fP\fIletter\fP
|
|
Insert the value of the alias named \fI_letter\fP. The symbol \fIletter\fP
|
|
represents a single alphabetic character from the
|
|
portable character set; implementations may support additional characters
|
|
as an extension. If the alias \fI_letter\fP contains
|
|
other editing commands, these commands shall be performed as part
|
|
of the insertion. If no alias \fI_letter\fP is enabled, this
|
|
command shall have no effect.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]~\fP
|
|
Convert, if the current character is a lowercase letter, to the equivalent
|
|
uppercase letter and \fIvice versa\fP, as
|
|
prescribed by the current locale. The current cursor position then
|
|
shall be advanced by one character. If the cursor was positioned
|
|
on the last character of the line, the case conversion shall occur,
|
|
but the cursor shall not advance. If the \fB'~'\fP
|
|
command is preceded by a \fIcount\fP, that number of characters shall
|
|
be converted, and the cursor shall be advanced to the
|
|
character position after the last character converted. If the \fIcount\fP
|
|
is larger than the number of characters after the
|
|
cursor, this shall not be considered an error; the cursor shall advance
|
|
to the last character on the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB].\fP
|
|
Repeat the most recent non-motion command, even if it was executed
|
|
on an earlier command line. If the previous command was
|
|
preceded by a \fIcount\fP, and no count is given on the \fB'.'\fP
|
|
command, the count from the previous command shall be
|
|
included as part of the repeated command. If the \fB'.'\fP command
|
|
is preceded by a \fIcount\fP, this shall override any
|
|
\fIcount\fP argument to the previous command. The \fIcount\fP specified
|
|
in the \fB'.'\fP command shall become the count for
|
|
subsequent \fB'.'\fP commands issued without a count.
|
|
.TP 7
|
|
\fB[\fP\fInumber\fP\fB]v\fP
|
|
Invoke the \fIvi\fP editor to edit the current command line in a temporary
|
|
file. When the
|
|
editor exits, the commands in the temporary file shall be executed
|
|
and placed in the command history. If a \fInumber\fP is
|
|
included, it specifies the command number in the command history to
|
|
be edited, rather than the current command line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]l\fP\ \ \ (ell)
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]\fP<space>
|
|
.sp
|
|
Move the current cursor position to the next character position. If
|
|
the cursor was positioned on the last character of the line,
|
|
the terminal shall be alerted and the cursor shall not be advanced.
|
|
If the \fIcount\fP is larger than the number of characters
|
|
after the cursor, this shall not be considered an error; the cursor
|
|
shall advance to the last character on the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]h\fP
|
|
Move the current cursor position to the \fIcount\fPth (default 1)
|
|
previous character position. If the cursor was positioned on
|
|
the first character of the line, the terminal shall be alerted and
|
|
the cursor shall not be moved. If the count is larger than the
|
|
number of characters before the cursor, this shall not be considered
|
|
an error; the cursor shall move to the first character on the
|
|
line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]w\fP
|
|
Move to the start of the next word. If the cursor was positioned on
|
|
the last character of the line, the terminal shall be
|
|
alerted and the cursor shall not be advanced. If the \fIcount\fP is
|
|
larger than the number of words after the cursor, this shall
|
|
not be considered an error; the cursor shall advance to the last character
|
|
on the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]W\fP
|
|
Move to the start of the next bigword. If the cursor was positioned
|
|
on the last character of the line, the terminal shall be
|
|
alerted and the cursor shall not be advanced. If the \fIcount\fP is
|
|
larger than the number of bigwords after the cursor, this
|
|
shall not be considered an error; the cursor shall advance to the
|
|
last character on the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]e\fP
|
|
Move to the end of the current word. If at the end of a word, move
|
|
to the end of the next word. If the cursor was positioned on
|
|
the last character of the line, the terminal shall be alerted and
|
|
the cursor shall not be advanced. If the \fIcount\fP is larger
|
|
than the number of words after the cursor, this shall not be considered
|
|
an error; the cursor shall advance to the last character on
|
|
the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]E\fP
|
|
Move to the end of the current bigword. If at the end of a bigword,
|
|
move to the end of the next bigword. If the cursor was
|
|
positioned on the last character of the line, the terminal shall be
|
|
alerted and the cursor shall not be advanced. If the
|
|
\fIcount\fP is larger than the number of bigwords after the cursor,
|
|
this shall not be considered an error; the cursor shall
|
|
advance to the last character on the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]b\fP
|
|
Move to the beginning of the current word. If at the beginning of
|
|
a word, move to the beginning of the previous word. If the
|
|
cursor was positioned on the first character of the line, the terminal
|
|
shall be alerted and the cursor shall not be moved. If the
|
|
\fIcount\fP is larger than the number of words preceding the cursor,
|
|
this shall not be considered an error; the cursor shall
|
|
return to the first character on the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]B\fP
|
|
Move to the beginning of the current bigword. If at the beginning
|
|
of a bigword, move to the beginning of the previous bigword.
|
|
If the cursor was positioned on the first character of the line, the
|
|
terminal shall be alerted and the cursor shall not be moved.
|
|
If the \fIcount\fP is larger than the number of bigwords preceding
|
|
the cursor, this shall not be considered an error; the cursor
|
|
shall return to the first character on the line.
|
|
.TP 7
|
|
\fB^\fP
|
|
Move the current cursor position to the first character on the input
|
|
line that is not a <blank>.
|
|
.TP 7
|
|
\fB$\fP
|
|
Move to the last character position on the current command line.
|
|
.TP 7
|
|
\fB0\fP
|
|
(Zero.) Move to the first character position on the current command
|
|
line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]|\fP
|
|
Move to the \fIcount\fPth character position on the current command
|
|
line. If no number is specified, move to the first
|
|
position. The first character position shall be numbered 1. If the
|
|
count is larger than the number of characters on the line, this
|
|
shall not be considered an error; the cursor shall be placed on the
|
|
last character on the line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]f\fP\fIc\fP
|
|
Move to the first occurrence of the character \fB'c'\fP that occurs
|
|
after the current cursor position. If the cursor was
|
|
positioned on the last character of the line, the terminal shall be
|
|
alerted and the cursor shall not be advanced. If the character
|
|
\fB'c'\fP does not occur in the line after the current cursor position,
|
|
the terminal shall be alerted and the cursor shall not
|
|
be moved.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]F\fP\fIc\fP
|
|
Move to the first occurrence of the character \fB'c'\fP that occurs
|
|
before the current cursor position. If the cursor was
|
|
positioned on the first character of the line, the terminal shall
|
|
be alerted and the cursor shall not be moved. If the character
|
|
\fB'c'\fP does not occur in the line before the current cursor position,
|
|
the terminal shall be alerted and the cursor shall not
|
|
be moved.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]t\fP\fIc\fP
|
|
Move to the character before the first occurrence of the character
|
|
\fB'c'\fP that occurs after the current cursor position.
|
|
If the cursor was positioned on the last character of the line, the
|
|
terminal shall be alerted and the cursor shall not be advanced.
|
|
If the character \fB'c'\fP does not occur in the line after the current
|
|
cursor position, the terminal shall be alerted and the
|
|
cursor shall not be moved.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]T\fP\fIc\fP
|
|
Move to the character after the first occurrence of the character
|
|
\fB'c'\fP that occurs before the current cursor position.
|
|
If the cursor was positioned on the first character of the line, the
|
|
terminal shall be alerted and the cursor shall not be moved.
|
|
If the character \fB'c'\fP does not occur in the line before the current
|
|
cursor position, the terminal shall be alerted and the
|
|
cursor shall not be moved.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB];\fP
|
|
Repeat the most recent \fBf\fP, \fBF\fP, \fBt\fP, or \fBT\fP command.
|
|
Any number argument on that previous command shall be
|
|
ignored. Errors are those described for the repeated command.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB],\fP
|
|
Repeat the most recent \fBf\fP, \fBF\fP, \fBt\fP, or \fBT\fP command.
|
|
Any number argument on that previous command shall be
|
|
ignored. However, reverse the direction of that command.
|
|
.TP 7
|
|
\fBa\fP
|
|
Enter insert mode after the current cursor position. Characters that
|
|
are entered shall be inserted before the next
|
|
character.
|
|
.TP 7
|
|
\fBA\fP
|
|
Enter insert mode after the end of the current command line.
|
|
.TP 7
|
|
\fBi\fP
|
|
Enter insert mode at the current cursor position. Characters that
|
|
are entered shall be inserted before the current
|
|
character.
|
|
.TP 7
|
|
\fBI\fP
|
|
Enter insert mode at the beginning of the current command line.
|
|
.TP 7
|
|
\fBR\fP
|
|
Enter insert mode, replacing characters from the command line beginning
|
|
at the current cursor position.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]c\fP\fImotion\fP
|
|
.sp
|
|
Delete the characters between the current cursor position and the
|
|
cursor position that would result from the specified motion
|
|
command. Then enter insert mode before the first character following
|
|
any deleted characters. If \fIcount\fP is specified, it shall
|
|
be applied to the motion command. A \fIcount\fP shall be ignored for
|
|
the following motion commands:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB0 ^ $ c
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
If the motion command is the character \fB'c'\fP , the current command
|
|
line shall be cleared and insert mode shall be
|
|
entered. If the motion command would move the current cursor position
|
|
toward the beginning of the command line, the character under
|
|
the current cursor position shall not be deleted. If the motion command
|
|
would move the current cursor position toward the end of
|
|
the command line, the character under the current cursor position
|
|
shall be deleted. If the \fIcount\fP is larger than the number
|
|
of characters between the current cursor position and the end of the
|
|
command line toward which the motion command would move the
|
|
cursor, this shall not be considered an error; all of the remaining
|
|
characters in the aforementioned range shall be deleted and
|
|
insert mode shall be entered. If the motion command is invalid, the
|
|
terminal shall be alerted, the cursor shall not be moved, and
|
|
no text shall be deleted.
|
|
.TP 7
|
|
\fBC\fP
|
|
Delete from the current character to the end of the line and enter
|
|
insert mode at the new end-of-line.
|
|
.TP 7
|
|
\fBS\fP
|
|
Clear the entire edit line and enter insert mode.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]r\fP\fIc\fP
|
|
Replace the current character with the character \fB'c'\fP . With
|
|
a number \fIcount\fP, replace the current and the
|
|
following \fIcount\fP-1 characters. After this command, the current
|
|
cursor position shall be on the last character that was
|
|
changed. If the \fIcount\fP is larger than the number of characters
|
|
after the cursor, this shall not be considered an error; all
|
|
of the remaining characters shall be changed.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]_\fP
|
|
Append a <space> after the current character position and then append
|
|
the last bigword in the previous input line after
|
|
the <space>. Then enter insert mode after the last character just
|
|
appended. With a number \fIcount\fP, append the
|
|
\fIcount\fPth bigword in the previous line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]x\fP
|
|
Delete the character at the current cursor position and place the
|
|
deleted characters in the save buffer. If the cursor was
|
|
positioned on the last character of the line, the character shall
|
|
be deleted and the cursor position shall be moved to the previous
|
|
character (the new last character). If the \fIcount\fP is larger than
|
|
the number of characters after the cursor, this shall not be
|
|
considered an error; all the characters from the cursor to the end
|
|
of the line shall be deleted.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]X\fP
|
|
Delete the character before the current cursor position and place
|
|
the deleted characters in the save buffer. The character
|
|
under the current cursor position shall not change. If the cursor
|
|
was positioned on the first character of the line, the terminal
|
|
shall be alerted, and the \fBX\fP command shall have no effect. If
|
|
the line contained a single character, the \fBX\fP command
|
|
shall have no effect. If the line contained no characters, the terminal
|
|
shall be alerted and the cursor shall not be moved. If the
|
|
\fIcount\fP is larger than the number of characters before the cursor,
|
|
this shall not be considered an error; all the characters
|
|
from before the cursor to the beginning of the line shall be deleted.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]d\fP\fImotion\fP
|
|
.sp
|
|
Delete the characters between the current cursor position and the
|
|
character position that would result from the motion command. A
|
|
number \fIcount\fP repeats the motion command \fIcount\fP times. If
|
|
the motion command would move toward the beginning of the
|
|
command line, the character under the current cursor position shall
|
|
not be deleted. If the motion command is \fBd\fP, the entire
|
|
current command line shall be cleared. If the \fIcount\fP is larger
|
|
than the number of characters between the current cursor
|
|
position and the end of the command line toward which the motion command
|
|
would move the cursor, this shall not be considered an
|
|
error; all of the remaining characters in the aforementioned range
|
|
shall be deleted. The deleted characters shall be placed in the
|
|
save buffer.
|
|
.TP 7
|
|
\fBD\fP
|
|
Delete all characters from the current cursor position to the end
|
|
of the line. The deleted characters shall be placed in the
|
|
save buffer.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]y\fP\fImotion\fP
|
|
.sp
|
|
Yank (that is, copy) the characters from the current cursor position
|
|
to the position resulting from the motion command into the
|
|
save buffer. A number \fIcount\fP shall be applied to the motion command.
|
|
If the motion command would move toward the beginning of
|
|
the command line, the character under the current cursor position
|
|
shall not be included in the set of yanked characters. If the
|
|
motion command is \fBy\fP, the entire current command line shall be
|
|
yanked into the save buffer. The current cursor position shall
|
|
be unchanged. If the \fIcount\fP is larger than the number of characters
|
|
between the current cursor position and the end of the
|
|
command line toward which the motion command would move the cursor,
|
|
this shall not be considered an error; all of the remaining
|
|
characters in the aforementioned range shall be yanked.
|
|
.TP 7
|
|
\fBY\fP
|
|
Yank the characters from the current cursor position to the end of
|
|
the line into the save buffer. The current character
|
|
position shall be unchanged.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]p\fP
|
|
Put a copy of the current contents of the save buffer after the current
|
|
cursor position. The current cursor position shall be
|
|
advanced to the last character put from the save buffer. A \fIcount\fP
|
|
shall indicate how many copies of the save buffer shall be
|
|
put.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]P\fP
|
|
Put a copy of the current contents of the save buffer before the current
|
|
cursor position. The current cursor position shall be
|
|
moved to the last character put from the save buffer. A \fIcount\fP
|
|
shall indicate how many copies of the save buffer shall be
|
|
put.
|
|
.TP 7
|
|
\fBu\fP
|
|
Undo the last command that changed the edit line. This operation shall
|
|
not undo the copy of any command line to the edit
|
|
line.
|
|
.TP 7
|
|
\fBU\fP
|
|
Undo all changes made to the edit line. This operation shall not undo
|
|
the copy of any command line to the edit line.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]k\fP
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]-\fP
|
|
Set the current command line to be the \fIcount\fPth previous command
|
|
line in the shell command history. If \fIcount\fP is
|
|
not specified, it shall default to 1. The cursor shall be positioned
|
|
on the first character of the new command. If a \fBk\fP or
|
|
\fB-\fP command would retreat past the maximum number of commands
|
|
in effect for this shell (affected by the \fIHISTSIZE\fP
|
|
environment variable), the terminal shall be alerted, and the command
|
|
shall have no effect.
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]j\fP
|
|
.TP 7
|
|
\fB[\fP\fIcount\fP\fB]+\fP
|
|
Set the current command line to be the \fIcount\fPth next command
|
|
line in the shell command history. If \fIcount\fP is not
|
|
specified, it shall default to 1. The cursor shall be positioned on
|
|
the first character of the new command. If a \fBj\fP or
|
|
\fB+\fP command advances past the edit line, the current command line
|
|
shall be restored to the edit line and the terminal shall be
|
|
alerted.
|
|
.TP 7
|
|
\fB[\fP\fInumber\fP\fB]G\fP
|
|
Set the current command line to be the oldest command line stored
|
|
in the shell command history. With a number \fInumber\fP,
|
|
set the current command line to be the command line \fInumber\fP in
|
|
the history. If command line \fInumber\fP does not exist, the
|
|
terminal shall be alerted and the command line shall not be changed.
|
|
.TP 7
|
|
\fB/\fP\fIpattern\fP<newline>
|
|
.sp
|
|
Move backwards through the command history, searching for the specified
|
|
pattern, beginning with the previous command line. Patterns
|
|
use the pattern matching notation described in \fIPattern Matching
|
|
Notation\fP , except
|
|
that the \fB'^'\fP character shall have special meaning when it appears
|
|
as the first character of \fIpattern\fP. In this case,
|
|
the \fB'^'\fP is discarded and the characters after the \fB'^'\fP
|
|
shall be matched only at the beginning of a line. Commands
|
|
in the command history shall be treated as strings, not as filenames.
|
|
If the pattern is not found, the current command line shall
|
|
be unchanged and the terminal is alerted. If it is found in a previous
|
|
line, the current command line shall be set to that line and
|
|
the cursor shall be set to the first character of the new command
|
|
line.
|
|
.LP
|
|
If \fIpattern\fP is empty, the last non-empty pattern provided to
|
|
\fB/\fP or \fB?\fP shall be used. If there is no previous
|
|
non-empty pattern, the terminal shall be alerted and the current command
|
|
line shall remain unchanged.
|
|
.TP 7
|
|
\fB?\fP\fIpattern\fP<newline>
|
|
.sp
|
|
Move forwards through the command history, searching for the specified
|
|
pattern, beginning with the next command line. Patterns use
|
|
the pattern matching notation described in \fIPattern Matching Notation\fP
|
|
, except that
|
|
the \fB'^'\fP character shall have special meaning when it appears
|
|
as the first character of \fIpattern\fP. In this case, the
|
|
\fB'^'\fP is discarded and the characters after the \fB'^'\fP shall
|
|
be matched only at the beginning of a line. Commands in
|
|
the command history shall be treated as strings, not as filenames.
|
|
If the pattern is not found, the current command line shall be
|
|
unchanged and the terminal alerted. If it is found in a following
|
|
line, the current command line shall be set to that line and the
|
|
cursor shall be set to the fist character of the new command line.
|
|
.LP
|
|
If \fIpattern\fP is empty, the last non-empty pattern provided to
|
|
\fB/\fP or \fB?\fP shall be used. If there is no previous
|
|
non-empty pattern, the terminal shall be alerted and the current command
|
|
line shall remain unchanged.
|
|
.TP 7
|
|
\fBn\fP
|
|
Repeat the most recent \fB/\fP or \fB?\fP command. If there is no
|
|
previous \fB/\fP or \fB?\fP, the terminal shall be
|
|
alerted and the current command line shall remain unchanged.
|
|
.TP 7
|
|
\fBN\fP
|
|
Repeat the most recent \fB/\fP or \fB?\fP command, reversing the direction
|
|
of the search. If there is no previous \fB/\fP or
|
|
\fB?\fP, the terminal shall be alerted and the current command line
|
|
shall remain unchanged.
|
|
.sp
|
|
.SH EXIT STATUS
|
|
.LP
|
|
The following exit values shall be returned:
|
|
.TP 7
|
|
\ \ \ \ 0
|
|
The script to be executed consisted solely of zero or more blank lines
|
|
or comments, or both.
|
|
.TP 7
|
|
1-125
|
|
A non-interactive shell detected a syntax, redirection, or variable
|
|
assignment error.
|
|
.TP 7
|
|
\ \ 127
|
|
A specified \fIcommand_file\fP could not be found by a non-interactive
|
|
shell.
|
|
.sp
|
|
.LP
|
|
Otherwise, the shell shall return the exit status of the last command
|
|
it invoked or attempted to invoke (see also the \fIexit\fP utility
|
|
in \fISpecial Built-In
|
|
Utilities\fP ).
|
|
.SH CONSEQUENCES OF ERRORS
|
|
.LP
|
|
See \fIConsequences of Shell Errors\fP .
|
|
.LP
|
|
\fIThe following sections are informative.\fP
|
|
.SH APPLICATION USAGE
|
|
.LP
|
|
Standard input and standard error are the files that determine whether
|
|
a shell is interactive when \fB-i\fP is not specified.
|
|
For example:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBsh > file
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
and:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBsh 2> file
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
create interactive and non-interactive shells, respectively. Although
|
|
both accept terminal input, the results of error
|
|
conditions are different, as described in \fIConsequences of Shell
|
|
Errors\fP ; in the
|
|
second example a redirection error encountered by a special built-in
|
|
utility aborts the shell.
|
|
.LP
|
|
A conforming application must protect its first operand, if it starts
|
|
with a plus sign, by preceding it with the \fB"--"\fP
|
|
argument that denotes the end of the options.
|
|
.LP
|
|
Applications should note that the standard \fIPATH\fP to the shell
|
|
cannot be assumed to be either \fB/bin/sh\fP or
|
|
\fB/usr/bin/sh\fP, and should be determined by interrogation of the
|
|
\fIPATH\fP returned by \fIgetconf\fP \fIPATH ,\fP ensuring that the
|
|
returned pathname is an absolute pathname and not a
|
|
shell built-in.
|
|
.LP
|
|
For example, to determine the location of the standard \fIsh\fP utility:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBcommand -v sh
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
On some implementations this might return:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB/usr/xpg4/bin/sh
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
Furthermore, on systems that support executable scripts (the \fB"#!"\fP
|
|
construct), it is recommended that applications using
|
|
executable scripts install them using \fIgetconf\fP \fB-v\fP to determine
|
|
the shell
|
|
pathname and update the \fB"#!"\fP script appropriately as it is being
|
|
installed (for example, with \fIsed\fP). For example:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB#
|
|
# Installation time script to install correct POSIX shell pathname
|
|
#
|
|
# Get list of paths to check
|
|
#
|
|
Sifs=$IFS
|
|
IFS=:
|
|
set $(getconf PATH)
|
|
IFS=$Sifs
|
|
#
|
|
# Check each path for 'sh'
|
|
#
|
|
for i in $@
|
|
do
|
|
if [ -f ${i}/sh ];
|
|
then
|
|
Pshell=${i}/sh
|
|
fi
|
|
done
|
|
#
|
|
# This is the list of scripts to update. They should be of the
|
|
# form '${name}.source' and will be transformed to '${name}'.
|
|
# Each script should begin:
|
|
#
|
|
# !INSTALLSHELLPATH -p
|
|
#
|
|
scripts="a b c"
|
|
#
|
|
# Transform each script
|
|
#
|
|
for i in ${scripts}
|
|
do
|
|
sed -e "s|INSTALLSHELLPATH|${Pshell}|" < ${i}.source > ${i}
|
|
done
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.SH EXAMPLES
|
|
.IP " 1." 4
|
|
Execute a shell command from a string:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBsh -c "cat myfile"
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
.IP " 2." 4
|
|
Execute a shell script from a file in the current directory:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBsh my_shell_cmds
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
.SH RATIONALE
|
|
.LP
|
|
The \fIsh\fP utility and the \fIset\fP special built-in utility share
|
|
a common
|
|
set of options.
|
|
.LP
|
|
The KornShell ignores the contents of \fIIFS\fP upon entry to the
|
|
script. A conforming application cannot rely on importing
|
|
\fIIFS .\fP One justification for this, beyond security considerations,
|
|
is to assist possible future shell compilers. Allowing
|
|
\fIIFS\fP to be imported from the environment prevents many optimizations
|
|
that might otherwise be performed via dataflow analysis
|
|
of the script itself.
|
|
.LP
|
|
The text in the STDIN section about non-blocking reads concerns an
|
|
instance of \fIsh\fP that has been invoked, probably by a
|
|
C-language program, with standard input that has been opened using
|
|
the O_NONBLOCK flag; see \fIopen\fP() in the System Interfaces volume
|
|
of IEEE\ Std\ 1003.1-2001. If the shell did not
|
|
reset this flag, it would immediately terminate because no input data
|
|
would be available yet and that would be considered the same
|
|
as end-of-file.
|
|
.LP
|
|
The options associated with a \fIrestricted shell\fP (command name
|
|
\fIrsh\fP and the \fB-r\fP option) were excluded because
|
|
the standard developers considered that the implied level of security
|
|
could not be achieved and they did not want to raise false
|
|
expectations.
|
|
.LP
|
|
On systems that support set-user-ID scripts, a historical trapdoor
|
|
has been to link a script to the name \fB-i\fP. When it is
|
|
called by a sequence such as:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBsh -
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
or by:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB#! usr/bin/sh -
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
the historical systems have assumed that no option letters follow.
|
|
Thus, this volume of IEEE\ Std\ 1003.1-2001 allows
|
|
the single hyphen to mark the end of the options, in addition to the
|
|
use of the regular \fB"--"\fP argument, because it was
|
|
considered that the older practice was so pervasive. An alternative
|
|
approach is taken by the KornShell, where real and effective
|
|
user/group IDs must match for an interactive shell; this behavior
|
|
is specifically allowed by this volume of
|
|
IEEE\ Std\ 1003.1-2001.
|
|
.TP 7
|
|
\fBNote:\fP
|
|
There are other problems with set-user-ID scripts that the two approaches
|
|
described here do not resolve.
|
|
.sp
|
|
.LP
|
|
The initialization process for the history file can be dependent on
|
|
the system start-up files, in that they may contain commands
|
|
that effectively preempt the user's settings of \fIHISTFILE\fP and
|
|
\fIHISTSIZE .\fP For example, function definition commands are
|
|
recorded in the history file, unless the \fIset\fP \fB-o\fP \fInolog\fP
|
|
option is
|
|
set. If the system administrator includes function definitions in
|
|
some system start-up file called before the \fIENV\fP file, the
|
|
history file is initialized before the user gets a chance to influence
|
|
its characteristics. In some historical shells, the history
|
|
file is initialized just after the \fIENV\fP file has been processed.
|
|
Therefore, it is implementation-defined whether changes made
|
|
to \fIHISTFILE\fP after the history file has been initialized are
|
|
effective.
|
|
.LP
|
|
The default messages for the various \fIMAIL -related\fP messages
|
|
are unspecified because they vary across implementations.
|
|
Typical messages are:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB"you have mail\\n"
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
or:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB"you have new mail\\n"
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
It is important that the descriptions of command line editing refer
|
|
to the same shell as that in IEEE\ Std\ 1003.1-2001
|
|
so that interactive users can also be application programmers without
|
|
having to deal with programmatic differences in their two
|
|
environments. It is also essential that the utility name \fIsh\fP
|
|
be specified because this explicit utility name is too firmly
|
|
rooted in historical practice of application programs for it to change.
|
|
.LP
|
|
Consideration was given to mandating a diagnostic message when attempting
|
|
to set \fIvi\fP-mode on terminals that do not support command line
|
|
editing. However, it is not historical
|
|
practice for the shell to be cognizant of all terminal types and thus
|
|
be able to detect inappropriate terminals in all cases.
|
|
Implementations are encouraged to supply diagnostics in this case
|
|
whenever possible, rather than leaving the user in a state where
|
|
editing commands work incorrectly.
|
|
.LP
|
|
In early proposals, the KornShell-derived \fIemacs\fP mode of command
|
|
line editing was included, even though the \fIemacs\fP
|
|
editor itself was not. The community of \fIemacs\fP proponents was
|
|
adamant that the full \fIemacs\fP editor not be standardized
|
|
because they were concerned that an attempt to standardize this very
|
|
powerful environment would encourage vendors to ship strictly
|
|
conforming versions lacking the extensibility required by the community.
|
|
The author of the original \fIemacs\fP program also
|
|
expressed his desire to omit the program. Furthermore, there were
|
|
a number of historical systems that did not include \fIemacs\fP,
|
|
or included it without supporting it, but there were very few that
|
|
did not include and support \fIvi\fP. The shell \fIemacs\fP command
|
|
line editing mode was finally omitted because it became
|
|
apparent that the KornShell version and the editor being distributed
|
|
with the GNU system had diverged in some respects. The author
|
|
of \fIemacs\fP requested that the POSIX \fIemacs\fP mode either be
|
|
deleted or have a significant number of unspecified
|
|
conditions. Although the KornShell author agreed to consider changes
|
|
to bring the shell into alignment, the standard developers
|
|
decided to defer specification at that time. At the time, it was assumed
|
|
that convergence on an acceptable definition would occur
|
|
for a subsequent draft, but that has not happened, and there appears
|
|
to be no impetus to do so. In any case, implementations are
|
|
free to offer additional command line editing modes based on the exact
|
|
models of editors their users are most comfortable with.
|
|
.LP
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|
Early proposals had the following list entry in vi Line Editing Insert
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|
Mode :
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|
.TP 7
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|
\fB\\\fP
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If followed by the \fIerase\fP or \fIkill\fP character, that character
|
|
shall be inserted into the input line. Otherwise, the
|
|
backslash itself shall be inserted into the input line.
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|
.sp
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|
.LP
|
|
However, this is not actually a feature of \fIsh\fP command line editing
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insert mode, but one of some historical terminal line
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|
drivers. Some conforming implementations continue to do this when
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|
the \fIstty\fP
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|
\fBiexten\fP flag is set.
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|
.SH FUTURE DIRECTIONS
|
|
.LP
|
|
None.
|
|
.SH SEE ALSO
|
|
.LP
|
|
\fIShell Command Language\fP , \fIcd\fP , \fIecho\fP , \fIexit\fP()
|
|
, \fIfc\fP , \fIpwd\fP , \fIread\fP() , \fIset\fP , \fIstty\fP , \fItest\fP
|
|
, \fIumask\fP() , \fIvi\fP , the System Interfaces volume of IEEE\ Std\ 1003.1-2001,
|
|
\fIdup\fP(), \fIexec\fP, \fIexit\fP(), \fIfork\fP(), \fIopen\fP(),
|
|
\fIpipe\fP(), \fIsignal\fP(), \fIsystem\fP(), \fIulimit\fP(), \fIumask\fP(),
|
|
\fIwait\fP()
|
|
.SH COPYRIGHT
|
|
Portions of this text are reprinted and reproduced in electronic form
|
|
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
|
|
-- Portable Operating System Interface (POSIX), The Open Group Base
|
|
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
|
|
Electrical and Electronics Engineers, Inc and The Open Group. In the
|
|
event of any discrepancy between this version and the original IEEE and
|
|
The Open Group Standard, the original IEEE and The Open Group Standard
|
|
is the referee document. The original Standard can be obtained online at
|
|
http://www.opengroup.org/unix/online.html .
|