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Re: [Help-bash] Different methods of running scripts; subshells and exec
From: |
Greg Wooledge |
Subject: |
Re: [Help-bash] Different methods of running scripts; subshells and execute privileges |
Date: |
Mon, 24 Aug 2015 12:17:01 -0400 |
User-agent: |
Mutt/1.4.2.3i |
On Mon, Aug 24, 2015 at 08:44:16AM -0700, Michael Convey wrote:
> > Subshells may be created explicitly by putting ( ) around a command,
> > or more commonly
>
> So is it possible to run a script in a true subshell? If so, is the
> following the only way to to do this?
>
> ???$ ???
> bash (/path/script)
> ???$ ???
> sh (/path/script)
> ???$ ???
> /path/script()
> ???
Parentheses have to go around the ENTIRE command. You can't stick them
in the middle.
Here are some examples of explicit subshells:
(cd /foo && make)
(cd /bar && make clean)
(unset DISPLAY; /some/terminal-or-X/editor)
(shopt -s dotglob nullglob; files=(*); echo "There are address@hidden files
here.")
What do these all have in common? There is a global side effect that
we DON'T want. So we do the job in a subshell, and the global side
effect (changing directory, unsetting environment variables, changing
shell options) goes away. That's the purpose of an explicit subshell.
There is no reason to wrap "sh /path/to/script" in an explicit subshell.
It's already going to fork a new process. If you were to do it anyway,
you would have to put the parentheses around the ENTIRE command:
(sh /path/to/script)
But again, it's silly. It accomplishes nothing.
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, (continued)
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Ken Irving, 2015/08/19
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Greg Wooledge, 2015/08/19
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Michael Convey, 2015/08/19
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Greg Wooledge, 2015/08/19
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Michael Convey, 2015/08/19
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Greg Wooledge, 2015/08/20
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Michael Convey, 2015/08/20
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Michael Convey, 2015/08/24
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Greg Wooledge, 2015/08/24
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Michael Convey, 2015/08/24
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges,
Greg Wooledge <=
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Michael Convey, 2015/08/24
- Re: [Help-bash] Different methods of running scripts; subshells and execute privileges, Greg Wooledge, 2015/08/24