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<A NAME="PAGENUM-37"><P>Page 37</P></A>
<TABLE>
<TR><TD>
</TD><TD>
\a
</TD><TD>
Alert (bell)
</TD></TR><TR><TD>
</TD><TD>
\b
</TD><TD>
Backspace
</TD></TR><TR><TD>
</TD><TD>
\c
</TD><TD>
Suppress trailing newline
</TD></TR><TR><TD>
</TD><TD>
\f
</TD><TD>
Form feed
</TD></TR><TR><TD>
</TD><TD>
\n
</TD><TD>
Newline
</TD></TR><TR><TD>
</TD><TD>
\r
</TD><TD>
Carriage return
</TD></TR><TR><TD>
</TD><TD>
\t
</TD><TD>
Horizontal tab
</TD></TR><TR><TD>
</TD><TD>
\v
</TD><TD>
Vertical tab
</TD></TR><TR><TD>
</TD><TD>
\\
</TD><TD>
Backslash
</TD></TR><TR><TD>
</TD><TD>
\nnn
</TD><TD>
The character whose ASCII code is
nnn (octal)
</TD></TR></TABLE>
<TABLE>
<TR><TD>
enable [_n][_all][name ...]
</TD><TD>
Enable and disable builtin shell commands. This allows the execution of a
disk command that has the same name as a shell builtin without specifying a
full pathname. If _n is used, each name is
disabled; otherwise, names are enabled. For example, to use the test binary found via the
PATH instead of the shell builtin version, type enable -n
test. If no arguments are given, a list of all enabled shell builtins
is printed. If only _n is supplied, a list of all disabled builtins is printed. If only
_all is supplied, the list printed includes all builtins, with an indication of whether or
not each is enabled. enable accepts _a as a synonym for
_all. The return value is 0 unless a name is not a shell builtin.
</TD></TR><TR><TD>
eval [arg ...]
</TD><TD>
The args are read and concatenated together into a single command. This
command is then read and executed by the shell, and its exit status is returned as the value
of the eval command. If there are no args, or only null arguments,
eval returns True.
<P>exec [[_] command [arguments]] If command is specified, it replaces the shell. No new process is created. The
arguments become the arguments to command. If the first argument is
_, the shell places a dash in the zeroth arg passed to command. This is what
login does. If the file cannot be executed for some reason, a noninteractive shell exits, unless the shell
variable no_exit_on_failed_exec exists, in which case it returns failure. An interactive
shell returns failure if the file cannot be executed. If command is not specified,
any redirections take effect in the current shell, and the return status is
0.
</TD></TR><TR><TD>
exit [n]
</TD><TD>
Cause the shell to exit with a status of
n. If n is omitted, the exit status is that of the last command executed. A trap on
exit is executed before the shell terminates.
</TD></TR><TR><TD>
export [_nf][name[=word]] ...
</TD><TD>
The supplied
names are marked for automatic export to the environment of
</TD></TR><TR><TD>
export _p
</TD><TD>
subsequently executed commands. If the
_f option is given, the names refer to functions. If no names are given, or if the
_p option is supplied, a list of all names that are exported in this shell is printed. The
_n option causes the export property to be removed from the named variables. An argument of
— disables option checking for the rest of the arguments.
export returns an exit status of 0 unless an
illegal option is encountered, one of the names is not a legal shell variable name, or
_f is supplied with a name that is not a function.
</TD></TR><TR><TD>
fc [_e ename][_nlr][first][last]
</TD><TD>
Fix command. In the first form, a range of commands from
first to last is selected
</TD></TR><TR><TD>
fc _s [pat=rep][cmd]
</TD><TD>
from the history list.
first and last may be specified as a string (to locate the
last command beginning with that string) or as a number (an index into the history
list, where a negative number is used as an offset from the current command number).
If last is not specified, it is set to the current command for listing (so that
fc _l _10 prints the last 10 commands) and to
first otherwise. If first is not specified, it is set to the previous command for editing and
_16 for listing.
</TD></TR><TR><TD>
</TD><TD>
The _n flag suppresses the command numbers when listing. The
-r flag reverses the order of the commands. If the
_l flag is given, the commands are listed on
standard output. Otherwise, the editor given by
ename is invoked on a file containing those commands. If
ename is not given, the value of the FCEDIT variable is used, and
the
</TD></TR></TABLE>
<A NAME="PAGENUM-38"><P>Page 38</P></A>
<TABLE>
<TR><TD>
</TD><TD>
value of EDITOR if FCEDIT is not set. If neither variable is set,
vi is used. When editing is complete, the edited commands are echoed and executed.
</TD></TR><TR><TD>
</TD><TD>
In the second form, command is reexecuted after each instance of
pat is replaced by rep. A useful alias to use with this is
r=fc _s, so that typing r cc runs the last command beginning with
cc and typing r reexecutes the last command.
</TD></TR><TR><TD>
</TD><TD>
If the first form is used, the return value is
0 unless an illegal option is encountered or first or
last specify history lines out of range. If the _e option is supplied,
the return value is the value of the last command executed or failure if an error
occurs with the temporary file of commands. If the second form is used, the return status
is that of the command reexecuted, unless cmd does not specify a valid history line,
in which case fc returns failure.
</TD></TR><TR><TD>
fg [jobspec]
</TD><TD>
Place jobspec in the foreground, and make it the current job. If
jobspec is not present, the shell's notion of the current job is used.
The return value is that of the command placed into the foreground, or failure if run when job control is
disabled or, when run with job control enabled, if
jobspec does not specify a valid job or jobspec specifies a job that was started without job control.
</TD></TR><TR><TD>
getopts optstring name [args]
</TD><TD>
getopts is used by shell procedures to parse positional parameters.
optstring contains the option letters to be recognized; if a letter is followed by a colon, the option
is expected to have an argument, which should be separated from it by
whitespace. Each time it is invoked, getopts places the next option in the shell variable
name, initializing name if it does not exist, and the index of the next argument to
be processed into the variable OPTIND. OPTIND is initialized to
1 each time the shell or a shell script is invoked.
When an option requires an argument, getopts places
that argument into the variable OPTARG. The shell does not reset
OPTIND automatically; it must be manually reset between multiple calls to
getopts within the same shell invocation if a new set of parameters is to be used.
</TD></TR><TR><TD>
</TD><TD>
getopts can report errors in two ways. If the first character of
optstring is a colon, silent error reporting is used. In normal operation, diagnostic messages are
printed when illegal options or missing option arguments are encountered. If the
variable OPTERR is set to 0, no error message will be displayed, even if the first character
of optstring is not a colon.
</TD></TR><TR><TD>
</TD><TD>
If an illegal option is seen, getopts places a question mark
(?) into name and, if not silent, prints an error message and unsets
OPTARG. If getopts is silent, the option character found is placed in
OP-TARG and no diagnostic message is printed.
</TD></TR><TR><TD>
</TD><TD>
If a required argument is not found, and
getopts is not silent, a question mark (?) is placed in
name, OPTARG is unset, and a diagnostic message is printed. If
getopts is silent, then a colon (:) is placed in
name and OPTARG is set to the option character found.
</TD></TR><TR><TD>
</TD><TD>
getopts normally parses the positional parameters, but if more arguments are
given in args, getopts parses those instead.
getopts returns True if an option, specified or unspecified, is found. It returns
False if the end of options is encountered or an
error occurs.
</TD></TR><TR><TD>
hash [_r][name]
</TD><TD>
For each name, the full pathname of the command is determined and
remembered. The -r option causes the shell to forget all remembered locations. If no
arguments are given, information about remembered commands is printed. An argument of
— disables option checking for the rest of the arguments. The return status is
True unless a name is not found or an illegal option is supplied.
</TD></TR><TR><TD>
help [pattern]
</TD><TD>
Display helpful information about built-in commands. If
pattern is specified, help gives detailed help on
all commands matching pattern; otherwise, a list of
the builtins is printed. The return status is 0 unless no command matches pattern.
</TD></TR></TABLE>
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