AT&T UNIX™PC Unix System V Users Manual - tenox

KSH ( 1 ) KSH ( l )
NAME
ksh - Korn shell command programming language
SYNOPSIS
ksh [ -acefhikmnorstuvx ] [ - o option ... ] [arg . . . ]
DESCRIPTION
Ksh is a command programming language that executes commands
read from a terminal or a file. See Invocation below for the
meaning of arguments to the Korn shell.
Definitions.
A metacharacter is one of the following characters:
; & ( ) I < > new-line space tab
A blank is a tab or a space. An identifier is a sequence of letters,
digits, or underscores starting with a letter or underscore.
Identifiers are used as names for aliases, functions, and named
parameters . A word is a sequence of characters separated by one
or more non-quoted metacharacters .
Commands.
A simple-command is a sequence of blank separated words which
may be preceded by a parameter assignment list (see Environment
below). The first word specifies the name of the command to be
executed. Except as specified below, the remaining words are
passed as arguments to the invoked command. The command
name is passed as argument 0 (see exec(2)). The value of a
simple-command is its exit status if it terminates normally, or
(octal) 200+status if it terminates abnormally (see signal(2) for a
list of status values).
A pipeline is a sequence of one or more commands separated by 1.
The standard output of each command but the last is connected
by a pipe(2) to the standard input of the next command. Each
command is run as a separate process; the Korn shell waits for the
last command to terminate. The exit status of a pipeline is the
exit status of the last command.
A list is a sequence of one or more pipelines separated by ;, &,
&&, or IL and optionally terminated by ;, &, or 1&. Of these five
symbols, ;, &, and 17 have equal precedence, which is lower than
that of && and II· The symbols && and II also have equal precedence.
A semicolon (;) causes sequential execution of the
preceding pipeline; an ampersand (&) causes asynchronous execution
of the preceding pipeline (i.e., the Korn shell does not wait for
that pipeline to finish). The symbol I& causes asynchronous execution
of the preceding command or pipeline with a two-way pipe
established to the parent shell. The standard input and output of
the spawned command can be written to and read from by the
parent Shell using the -p option of the special commands read
and print described later. Only one such command can be active
at any given time. The symbol && (II) causes the list following it
to be executed only if the preceding pipeline returns a zero value.
An arbitrary number of new-lines may appear in a list, instead of
semicolons, to delimit commands.
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