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• more on pipelines vs subshells

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• remove some superfluous spaces
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tg 2009-09-06 18:17:51 +00:00
parent 9dd98da40d
commit ce24c5da13
1 changed files with 12 additions and 5 deletions
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@ -1,4 +1,4 @@
.\" $MirOS: src/bin/mksh/mksh.1,v 1.182 2009/09/06 17:55:54 tg Exp $ .\" $MirOS: src/bin/mksh/mksh.1,v 1.183 2009/09/06 18:17:51 tg Exp $
.\" $OpenBSD: ksh.1,v 1.129 2009/05/28 06:09:06 jmc Exp $ .\" $OpenBSD: ksh.1,v 1.129 2009/05/28 06:09:06 jmc Exp $
.\"- .\"-
.\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
@ -406,6 +406,13 @@ last is piped (see
.Xr pipe 2 ) .Xr pipe 2 )
to the standard input of the following command. to the standard input of the following command.
The exit status of a pipeline is that of its last command. The exit status of a pipeline is that of its last command.
All commands of a pipeline are executed in separate subshells;
this is allowed by POSIX but differs from both variants of
.At
.Nm ksh ,
where all but the last command were executed in subshells; see the
.Ic read
builtin's description for implications and workarounds.
A pipeline may be prefixed by the A pipeline may be prefixed by the
.Ql \&! .Ql \&!
reserved word which causes the exit status of the pipeline to be logically reserved word which causes the exit status of the pipeline to be logically
@ -1987,7 +1994,7 @@ does not exist, it is created; if it does exist, is a regular file, and the
.Ic noclobber .Ic noclobber
option is set, an error occurs; otherwise, the file is truncated. option is set, an error occurs; otherwise, the file is truncated.
Note that this means the command Note that this means the command
.Ic cmd \*(Lt foo \*(Gt foo .Ic cmd \*(Ltfoo \*(Gtfoo
will open will open
.Ar foo .Ar foo
for reading and then truncate it when it opens it for writing, before for reading and then truncate it when it opens it for writing, before
@ -2135,7 +2142,7 @@ Redirections are processed after
pipelines are created and in the order they are given, so the following pipelines are created and in the order they are given, so the following
will print an error with a line number prepended to it: will print an error with a line number prepended to it:
.Pp .Pp
.D1 $ cat /foo/bar 2\*(Gt&1 \*(Gt /dev/null \*(Ba cat \-n .D1 $ cat /foo/bar 2\*(Gt&1 \*(Gt/dev/null \*(Ba cat \-n
.Pp .Pp
File descriptors created by input/output redirections are private to the File descriptors created by input/output redirections are private to the
Korn shell, but passed to sub-processes if Korn shell, but passed to sub-processes if
@ -4049,8 +4056,8 @@ Simple redirections of standard error do not affect the output of the
.Ic time .Ic time
command: command:
.Pp .Pp
.Dl $ time sleep 1 2\*(Gt afile .Dl $ time sleep 1 2\*(Gtafile
.Dl $ { time sleep 1; } 2\*(Gt afile .Dl $ { time sleep 1; } 2\*(Gtafile
.Pp .Pp
Times for the first command do not go to Times for the first command do not go to
.Dq afile , .Dq afile ,