- Document trap's -l option and the behaviour of a missing action or a single
dash. - Discourage the omission of the action. PR: 70985 [1] Submitted by: Martin Kammerhofer
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2020-12-20 02:59:44 +00:00
svn path=/head/; revision=153246
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bin/sh/sh.1
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bin/sh/sh.1
@ -32,7 +32,7 @@
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.\" from: @(#)sh.1 8.6 (Berkeley) 5/4/95
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.\" $FreeBSD$
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.\"
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.Dd December 4, 2005
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.Dd December 8, 2005
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.Dt SH 1
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.Os
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.Sh NAME
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@ -1957,6 +1957,7 @@ The first output line shows the user and system times for the shell
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itself, the second one contains the user and system times for the
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children.
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.It Ic trap Oo Ar action Oc Ar signal ...
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.It Ic trap Fl l
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Cause the shell to parse and execute
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.Ar action
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when any specified
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@ -1968,14 +1969,25 @@ In addition, the pseudo-signal
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may be used to specify an action that is performed when the shell terminates.
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The
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.Ar action
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may be null or omitted;
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may be an empty string or a dash
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.Pq Ar - ;
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the former causes the specified signal to be ignored
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and the latter causes the default action to be taken.
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Omitting the
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.Ar action
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is another way to request the default action, for compatibility reasons this
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usage is not recommended though.
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When the shell forks off a subshell,
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it resets trapped (but not ignored) signals to the default action.
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The
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.Ic trap
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command has no effect on signals that were ignored on entry to the shell.
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.Pp
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Option
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.Fl l
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causes the
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.Ic trap
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command to display a list of valid signal names.
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.It Ic type Op Ar name ...
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Interpret each
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.Ar name
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