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Clean-up:

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Fix grammar and spelling nits.
	Use .Dq and .Qq where appropriate.
	Divorce trailing punctuation from quoted elements.
	Use .Dq instead of .Xr for builtins.
	Remove trailing whitespace and blank lines.

PR:	13340
This commit is contained in:
Sheldon Hearn 1999-08-30 10:13:04 +00:00
parent e5b502affd
commit 6b15476ec9
1 changed files with 160 additions and 69 deletions
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229
bin/sh/sh.1
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@ -115,7 +115,7 @@ of your home directory
substituting for
.Pa .shinit
any filename you wish.
If commandline arguments besides the options have been
If command line arguments besides the options have been
specified, then the shell treats the first argument as the
name of a file from which to read commands (a shell script), and
the remaining arguments are set as the positional parameters
@ -135,13 +135,13 @@ scripts.
All of the single letter options to
.Nm
have a corresponding name that can be used as an argument to the
.Xr set 1
.Dq set
builtin (described later). These names are provided next to the
single letter option in the descriptions below. Specifying a dash
.Dq -
enables the option, while using a plus
.Dq +
disables the option. A
disables the option. A
.Dq --
or plain
.Dq -
@ -156,12 +156,12 @@ completion.
.Pq UNIMPLEMENTED
.It Fl C Li noclobber
Don't overwrite existing files with
.Dq >.
.Dq > .
.Pq UNIMPLEMENTED
.It Fl E Li emacs
Enable the built-in
.Xr emacs 1
commandline editor (disables
command line editor (disables
.Fl V
if it has been set).
.It Fl e Li errexit
@ -201,20 +201,21 @@ after
and ignores the contents of the
.Ev ENV
variable.
.It Fl s Li stdin
Read commands from standard input (set automatically
if no file arguments are present). This option has
no effect when set after the shell has already started
running (i.e. with
.Xr set 1 Ns ).
running (i.e. when set with the
.Dq set
command).
.It Fl T Li asynctraps
When waiting for a child, execute traps immediately. If this option is
not set, traps are executed after the child exits, as specified in
.St -p1003.2
This nonstandard option is useful to put guarding shells around childs
that block signals. The surrounding shell may kill the child or it may
just return control to the tty and leave the child alone, like this:
This nonstandard option is useful for putting guarding shells around
children that block signals. The surrounding shell may kill the child
or it may just return control to the tty and leave the child alone,
like this:
.Bd -literal -offset indent
sh -T -c "trap 'exit 1' 2 ; some-blocking-program"
.Ed
@ -227,7 +228,7 @@ shell is not interactive, exit immediately.
.It Fl V Li vi
Enable the built-in
.Xr vi 1
commandline editor (disables
command line editor (disables
.Fl E
if it has been set).
.It Fl v Li verbose
@ -246,7 +247,9 @@ argument, hence multi-word strings must be quoted.
The shell reads input in terms of lines from a file and breaks
it up into words at whitespace (blanks and tabs), and at
certain sequences of
characters that are special to the shell called ``operators''.
characters called
.Dq operators ,
which are special to the shell.
There are two types of operators: control operators and
redirection operators (their meaning is discussed later).
The following is a list of valid operators:
@ -294,12 +297,15 @@ for if then until while
.Ed
.Ss Aliases
An alias is a name and corresponding value set using the
.Xr alias 1
.Dq alias
builtin command. Whenever a reserved word may occur (see above),
and after checking for reserved words, the shell
checks the word to see if it matches an alias. If it does,
it replaces it in the input stream with its value. For example,
if there is an alias called ``lf'' with the value ``ls -F'',
if there is an alias called
.Dq lf
with the value
.Dq ls -F ,
then the input
.Bd -literal -offset indent
lf foobar <return>
@ -329,18 +335,21 @@ If a simple command has been recognized, the shell performs
the following actions:
.Bl -enum
.It
Leading words of the form ``name=value'' are
stripped off and assigned to the environment of
Leading words of the form
.Dq name=value
are stripped off and assigned to the environment of
the simple command. Redirection operators and
their arguments (as described below) are stripped
off and saved for processing.
.It
The remaining words are expanded as described in
the section called ``Expansions'', and the
first remaining word is considered the command
the section called
.Sx Word Expansions ,
and the first remaining word is considered the command
name and the command is located. The remaining
words are considered the arguments of the command.
If no command name resulted, then the ``name=value''
If no command name resulted, then the
.Dq name=value
variable assignments recognized in 1) affect the
current shell.
.It
@ -379,7 +388,8 @@ duplicate stdout (or n1) to n2.
close stdout (or n)
.El
.Pp
The following redirection is often called a ``here-document''.
The following redirection is often called a
.Dq here-document .
.Bd -literal -offset indent
[n]<< delimiter
here-doc-text...
@ -392,8 +402,13 @@ input, or file descriptor n if it is specified. If the delimiter
as specified on the initial line is quoted, then the here-doc-text
is treated literally, otherwise the text is subjected to
parameter expansion, command substitution, and arithmetic
expansion (as described in the section on ``Expansions''). If
the operator is ``<<-'' instead of ``<<'', then leading tabs
expansion (as described in the section on
.Sx Word Expansions ) .
If the operator is
.Dq <<-
instead of
.Dq << ,
then leading tabs
in the here-doc-text are stripped.
.Ss Search and Execution
There are three types of commands: shell functions,
@ -421,13 +436,15 @@ program in the filesystem (as described in the next section).
When a normal program is executed, the shell runs the program,
passing the arguments and the environment to the
program. If the program is not a normal executable file
(i.e., if it does not begin with the "magic number" whose
(i.e. if it does not begin with the
.Qq magic number
whose
.Tn ASCII
representation is "#!", so
.Fn execve
returns
.Er ENOEXEC
then) the shell
representation is
.Qq #! ,
resulting in an ENOEXEC return value from
.Fn execve )
the shell
will interpret the program in a subshell. The child shell
will reinitialize itself in this case, so that the effect will
be as if a new shell had been invoked to handle the ad-hoc shell
@ -437,7 +454,8 @@ the parent shell will be remembered by the child.
Note that previous versions of this document
and the source code itself misleadingly and sporadically
refer to a shell script without a magic number
as a "shell procedure".
as a
.Qq shell procedure .
.Ss Path Search
When locating a command, the shell first looks to see if
it has a shell function by that name. Then it looks for a
@ -562,11 +580,19 @@ command and immediately proceed onto the next command;
otherwise it waits for the command to terminate before
proceeding to the next one.
.Ss Short-Circuit List Operators
``&&'' and ``||'' are AND-OR list operators. ``&&'' executes
the first command, and then executes the second command
if the exit status of the first command is zero. ``||''
.Dq &&
and
.Dq ||
are AND-OR list operators.
.Dq &&
executes the first command, and then executes the second command
if the exit status of the first command is zero.
.Dq ||
is similar, but executes the second command if the exit
status of the first command is nonzero. ``&&'' and ``||''
status of the first command is nonzero.
.Dq &&
and
.Dq ||
both have the same priority.
.Ss Flow-Control Constructs -- if, while, for, case
The syntax of the if command is
@ -600,7 +626,10 @@ done
.Pp
The words are expanded, and then the list is executed
repeatedly with the variable set to each word in turn. do
and done may be replaced with ``{'' and ``}''.
and done may be replaced with
.Dq {
and
.Dq } .
.Pp
The syntax of the break and continue command is
.Bd -literal -offset indent
@ -621,7 +650,9 @@ esac
.Ed
.Pp
The pattern can actually be one or more patterns (see Shell
Patterns described later), separated by ``|'' characters.
Patterns described later), separated by
.Dq |
characters.
.Ss Grouping Commands Together
Commands may be grouped by writing either
.Bd -literal -offset indent
@ -652,7 +683,10 @@ name ( ) command
A function definition is an executable statement; when
executed it installs a function named name and returns an
exit status of zero. The command is normally a list
enclosed between ``{'' and ``}''.
enclosed between
.Dq {
and
.Dq } .
.Pp
Variables may be declared to be local to a function by
using a local command. This should appear as the first
@ -674,7 +708,10 @@ variable x declared inside f, not to the global variable
named x.
.Pp
The only special parameter than can be made local is
``-''. Making ``-'' local any shell options that are
.Dq - .
Making
.Dq -
local causes any shell options that are
changed via the set command inside the function to be
restored to their original values when the function
returns.
@ -701,9 +738,9 @@ must not be numeric. A parameter can also be denoted by a number
or a special character as explained below.
.Ss Positional Parameters
A positional parameter is a parameter denoted by a number (n > 0).
The shell sets these initially to the values of its commandline
The shell sets these initially to the values of its command line
arguments that follow the name of the shell script. The
.Xr set 1
.Dq set
builtin can also be used to set or reset them.
.Ss Special Parameters
A special parameter is a parameter denoted by one of the following
@ -723,7 +760,13 @@ parameter expands as a separate argument.
If there are no positional parameters, the
expansion of @ generates zero arguments, even when @ is
double-quoted. What this basically means, for example, is
if $1 is ``abc'' and $2 is ``def ghi'', then "$@" expands to
if $1 is
.Dq abc
and $2 is
.Dq def ghi ,
then
.Qq $@
expands to
the two arguments:
.Bd -literal -offset indent
"abc" "def ghi"
@ -896,7 +939,9 @@ the command is enclosed as follows:
$(command)
.Ed
.Pp
or (``backquoted'' version):
or (
.Dq backquoted
version):
.Bd -literal -offset indent
`command`
.Ed
@ -946,23 +991,38 @@ a pattern cannot match a string starting with a period
unless the first character of the pattern is a period.
The next section describes the patterns used for both
Pathname Expansion and the
.Xr case 1
.Dq case
command.
.Ss Shell Patterns
A pattern consists of normal characters, which match themselves,
and meta-characters. The meta-characters are
``!'', ``*'', ``?'', and ``[''. These characters lose
their special meanings if they are quoted. When command
or variable substitution is performed and the dollar sign
or back quotes are not double quoted, the value of the
.Dq ! ,
.Dq * ,
.Dq ? ,
and
.Dq [ .
These characters lose their special meanings if they are quoted.
When command or variable substitution is performed and the dollar sign
or back quotes are not double-quoted, the value of the
variable or the output of the command is scanned for these
characters and they are turned into meta-characters.
.Pp
An asterisk (``*'') matches any string of characters. A
An asterisk
.Dq *
matches any string of characters. A
question mark matches any single character. A left
bracket (``['') introduces a character class. The end of
the character class is indicated by a ``]''; if the ``]''
is missing then the ``['' matches a ``['' rather than
bracket
.Dq [
introduces a character class. The end of
the character class is indicated by a
.Dq ] ;
if the
.Dq ]
is missing then the
.Dq [
matches a
.Dq [
rather than
introducing a character class. A character class matches
any of the characters between the square brackets. A
range of characters may be specified using a minus sign.
@ -970,8 +1030,12 @@ The character class may be complemented by making an
exclamation point the first character of the character
class.
.Pp
To include a ``]'' in a character class, make it the first
character listed (after the ``!'', if any). To include a
To include a
.Dq ]
in a character class, make it the first
character listed (after the
.Dq ! ,
if any). To include a
minus sign, make it the first or last character listed.
.Ss Builtins
This section lists the builtin commands which
@ -999,8 +1063,15 @@ for the file. If it is not found in the
it is sought in the current working directory.
.It alias [ name[=string] ... ]
If name=string is specified, the shell defines the
alias ``name'' with value ``string''. If just ``name''
is specified, the value of the alias ``name'' is printed.
alias
.Dq name
with value
.Dq string .
If just
.Dq name
is specified, the value of the alias
.Dq name
is printed.
With no arguments, the alias builtin prints the
names and values of all defined aliases (see unalias).
.It bg [ job ] ...
@ -1137,7 +1208,7 @@ it finds them. The -r option causes the hash command
to delete all the entries in the hash table except
for functions.
.It jobid [ job ]
Print the process id's of the processes in the job.
Print the process id's of the processes in the job.
If the job argument is omitted, use the current job.
.It jobs
This command lists out all the background processes
@ -1200,15 +1271,19 @@ variables.
.It
If options are given, it sets the specified option
flags, or clears them as described in the section
called ``Argument List Processing''.
called
.Sx Argument List Processing .
.It
The third use of the set command is to set the values
of the shell's positional parameters to the specified
args. To change the positional parameters without
changing any options, use ``--'' as the first argument
changing any options, use
.Dq --
as the first argument
to set. If no args are present, the set command
will clear all the positional parameters (equivalent
to executing ``shift $#''.
to executing
.Dq shift $# .
.El
.Pp
.It setvar variable value
@ -1243,19 +1318,31 @@ the command is printed.
.It ulimit [ -HSacdflmnust ] [ limit ]
Set or display resource limits (see
.Xr getrlimit 2 ).
If ``limit'' is specified, the named resource will be set;
If
.Dq limit
is specified, the named resource will be set;
otherwise the current resource value will be displayed.
.Pp
If ``-H'' is specified, the hard limits will be
If
.Dq -H
is specified, the hard limits will be
set or displayed. While everybody is allowed to reduce a
hard limit, only the superuser can increase it. Option ``-S''
hard limit, only the superuser can increase it. Option
.Dq -S
specifies the soft limits instead. When displaying limits,
only one of ``-S'' or ``-H'' can be given. The default is
only one of
.Dq -S
or
.Dq -H
can be given. The default is
to display the soft limits, and to set both, the hard and
the soft limits.
.Pp
Option ``-a'' requests to display all resources. The parameter
``limit'' is not acceptable in this mode.
Option
.Dq -a
requests to display all resources. The parameter
.Dq limit
is not acceptable in this mode.
.Pp
The remaining options specify which resource value is to be
displayed or modified. They are mutually exclusive.
@ -1288,8 +1375,12 @@ to the specified
octal value. If the argument is omitted, the
umask value is printed.
.It unalias [-a] [name]
If ``name'' is specified, the shell removes that alias.
If ``-a'' is specified, all aliases are removed.
If
.Dq name
is specified, the shell removes that alias.
If
.Dq -a
is specified, all aliases are removed.
.It unset name ...
The specified variables and functions are unset and
unexported. If a given name corresponds to both a
@ -1306,7 +1397,7 @@ When
.Nm
is being used interactively from a terminal, the current command
and the command history (see fc in Builtins) can be edited using vi-mode
commandline editing. This mode uses commands similar
command line editing. This mode uses commands similar
to a subset of those described in the vi man page.
The command 'set -o vi' enables vi-mode editing and places
.Nm
@ -1316,7 +1407,7 @@ can be switched between insert mode and command mode by typing <ESC>.
Hitting <return> while in command mode will pass the line to the shell.
.Pp
Similarly, the 'set -o emacs' command can be used to enable a subset of
emacs-style commandline editing features.
emacs-style command line editing features.
.Sh SEE ALSO
.Xr expr 1 ,
.Xr test 1