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sh(1): Add/improve information about exit status of commands.

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This commit is contained in:
Jilles Tjoelker 2014-11-14 17:11:28 +00:00
parent 8146bcfea1
commit b1f6059232
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=274515
1 changed files with 24 additions and 10 deletions
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34
bin/sh/sh.1
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@ -32,7 +32,7 @@
.\" from: @(#)sh.1 8.6 (Berkeley) 5/4/95
.\" $FreeBSD$
.\"
.Dd November 7, 2014
.Dd November 14, 2014
.Dt SH 1
.Os
.Sh NAME
@ -795,10 +795,13 @@ should indicate the various exit codes and what they mean.
Additionally, the built-in commands return exit codes, as does
an executed shell function.
.Pp
If a command is terminated by a signal, its exit status is 128 plus
the signal number.
Signal numbers are defined in the header file
.In sys/signal.h .
If a command is terminated by a signal, its exit status is greater than 128.
The signal name can be found by passing the exit status to
.Li kill -l .
.Pp
If there is no command word,
the exit status is the exit status of the last command substitution executed,
or zero if the command does not contain any command substitutions.
.Ss Complex Commands
Complex commands are combinations of simple commands
with control operators or keywords, together creating a larger complex
@ -818,7 +821,8 @@ function definition
.El
.Pp
Unless otherwise stated, the exit status of a command is
that of the last simple command executed by the command.
that of the last simple command executed by the command,
or zero if no simple command was executed.
.Ss Pipelines
A pipeline is a sequence of one or more commands separated
by the control operator
@ -902,6 +906,8 @@ The format for running a command in background is:
If the shell is not interactive, the standard input of an
asynchronous command is set to
.Pa /dev/null .
.Pp
The exit status is zero.
.Ss Lists (Generally Speaking)
A list is a sequence of zero or more commands separated by
newlines, semicolons, or ampersands,
@ -940,6 +946,13 @@ command is:
.Ic fi
.Ed
.Pp
The exit status is that of selected
.Ic then
or
.Ic else
list,
or zero if no list was selected.
.Pp
The syntax of the
.Ic while
command is:
@ -960,6 +973,9 @@ in place of
which causes it to
repeat until the exit status of the first list is zero.
.Pp
The exit status is that of the last execution of the second list,
or zero if it was never executed.
.Pp
The syntax of the
.Ic for
command is:
@ -1040,10 +1056,6 @@ continuing until a list terminated with
or the end of the
.Ic case
command.
The exit code of the
.Ic case
command is the exit code of the last command executed in the list or
zero if no patterns were matched.
.Ss Grouping Commands Together
Commands may be grouped by writing either
.Pp
@ -1131,6 +1143,8 @@ and the syntax is:
The
.Ic local
command is implemented as a built-in command.
The exit status is zero
unless the command is not in a function or a variable name is invalid.
.Pp
When a variable is made local, it inherits the initial
value and exported and readonly flags from the variable