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Correct description of the trap command (make it posix compatible) 

and add a couple more examples.   Also terminate a few sentences...
This commit is contained in:
kre 2017-04-29 15:26:44 +00:00
parent 51c4dfe49c
commit d778b916e6
1 changed files with 30 additions and 8 deletions
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38
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@ -1,4 +1,4 @@
.\" $NetBSD: sh.1,v 1.131 2017/04/14 08:48:01 abhinav Exp $
.\" $NetBSD: sh.1,v 1.132 2017/04/29 15:26:44 kre Exp $
.\" Copyright (c) 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
@ -31,7 +31,7 @@
.\"
.\" @(#)sh.1 8.6 (Berkeley) 5/4/95
.\"
.Dd March 20, 2017
.Dd April 29, 2017
.Dt SH 1
.ds flags abCEeFfhnuvxIimpqV
.Os
@ -2037,7 +2037,8 @@ positional parameters (
.Dq $# )
before the shift.
.It trap Oo Fl l Oc
.It trap Oo Ar action Oc Ar signal ...
.It trap Ar action signal ...
.It trap Ar N signal ...
Cause the shell to parse and execute action when any of the specified
signals are received.
The signals are specified by signal number or as the name of the signal.
@ -2051,9 +2052,20 @@ the action is executed when the shell exits.
may be null, which cause the specified signals to be ignored.
With
.Ar action
omitted or set to
set to
.Sq -
the specified signals are set to their default action.
If the first
.Ar signal
is specified in its numeric form, then
.Ar action
can be ommitted to achieve the same effect.
This archaic,
but still standard,
form should not be relied upon, use the explicit
.Sq -
action.
.Pp
When the shell forks off a subshell, it resets trapped (but not ignored)
signals to the default action.
On non-interactive shells, the
@ -2077,21 +2089,31 @@ Examples:
.Pp
.Dl trap
.Pp
List trapped signals and their corresponding action
List trapped signals and their corresponding action.
.Pp
.Dl trap -l
.Pp
Print a list of valid signals
Print a list of valid signals.
.Pp
.Dl trap '' INT QUIT tstp 30
.Pp
Ignore signals INT QUIT TSTP USR1
Ignore signals INT QUIT TSTP USR1.
.Pp
.Dl trap date INT
.Pp
Run the
.Dq date
command (print the date) upon receiving signal INT
command (print the date) upon receiving signal INT.
.Pp
.Dl trap HUP INT
.Pp
Run the
.Dq HUP
command upon receiving signal INT.
.Pp
.Dl trap 1 2
.Pp
Reset the actions for signals 1 (HUP) and 2 (INT) to their defaults.
.It type Op Ar name ...
Interpret each name as a command and print the resolution of the command
search.