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Full Discussion: How to run several bash commands put in bash command line?
Top Forums Shell Programming and Scripting How to run several bash commands put in bash command line? Post 303011747 by rbatte1 on Tuesday 23rd of January 2018 06:11:47 AM
Old 01-23-2018
What you originally have is more like saying "Run echo ${PATH} in the background and (ignoring if it works or not) run echo have a nice day! in the foreground"

Your output may not always be consistent. In this very simple case it probably always will be but more complex calls could have the output from either displayed first or even interleaved if you have two long running processes that output multiple lines. Can you tell us what you are trying to achieve here?


If you have a cmd1 ; cmd2 ; cmd3, these run sequentially. There is no return code checking done, it just runs one after the other.

If you have a cmd1 & cmd2 & cmd3 &, these run in the background (so disconnected from your STDIN (usually keyboard) and may independently write output to STDOUT (usually screen) ) and because cmd3 has a trailing & putting it in the background, you get dropped back to the shell (or calling program) and can carry on with other work. This may or may not be what you wanted.

If you have a mixture then you have to interpret what will happen. You can also add conditional execution, so cmd1 && cmd2 || cmd3 will run cmd1. If there is a zero return code (deemed as success) then run cmd2. If either cmd1 or cmd2 have a non-zero return code (deemed as a failure) then run cmd3

This can be quite compact but often can get complicated to interpret, so most people a re more explicit with something more like:
Code:
cmd1
RC=$?
if [ $RC -eq 0 ]
then
   cmd2
   RC=$?
fi

if [ $RC -ne 0 ]
then
   cmd3
fi


Does this help, or just confuse? Apologies if it is the latter.


Robin
 

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LEARN ABOUT SUNOS

gst-complete

gst-complete-0.8(1)						   User Commands					       gst-complete-0.8(1)

NAME

       gst-complete-0.8, gst-complete - perform bash completion for gst-launch command lines

SYNOPSIS

       complete -Cgst-complete-0.8 gst-launch

       gst-complete [--gst-list-mm] [--gst-mm=string] [--print]

DESCRIPTION

       gst-complete-0.8 enables bash to provide context-sensitive tab completion for gst-launch command lines. See gst-launch(1) for the syntax of
       gst-launch command lines.

       You must have a version of bash that supports programmable completion. Such versions of bash provide the complete built-in command.

       gst-complete is a wrapper script that runs the latest installed version of gst-complete-X.X. For example, if both gst-complete-0.7 and gst-
       complete-0.8 are installed on your system, gst-complete runs gst-complete-0.8.

OPTIONS

       The following options are supported by gst-complete-0.8 and gst-complete:

       --help	       Display detailed usage message. You can also use -? to specify this option.

       The following options are supported by gst-complete only:

       --gst-list-mm   List found major/minor versions. This option displays the versions that are available.

       --gst-mm=string Force  major/minor  version.  This  option  enables you to specify a specific version to run, if you do not want to run the
		       default version.

       --print	       Print wrapped command line. This option displays the command that will be run, and then runs the command.

EXAMPLES

       Example 1: Generating the Registry of Available Plugins by Running gst-compprep

       Run the following command in your .bash_profile or other appropriate place:

       example% complete -C gst-complete-0.8 gst-launch

       Example 2: Running the Wrapper Script and Displaying the Command Name

       example% gst-complete --print
       /usr/bin/gst-complete-0.8

FILES

       The following files are used by this application:

       /usr/bin/gst-complete-0.Executable for bash completion for gst-launch

       /usr/bin/gst-complete   Wrapper script that runs the latest installed version of gst-complete-X.X

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWgnome-media		   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |External			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       gst-compprep(1), gst-feedback(1), gst-inspect(1), gst-launch(1), gst-launch-ext(1), gst-md5sum(1), gst-register(1), gst-thumbnail(1),  gst-
       typefind(1), gst-xmlinspect(1), gst-xmllaunch(1), gstreamer-properties(1), libgstreamer-0.8(3), libgstgetbits(3)

NOTES

       Original man page written by the GStreamer team at http://gstreamer.net/.

       Updated by Brian Cameron, Sun Microsystems Inc., 2004.

SunOS 5.10							    14 Oct 2004 					       gst-complete-0.8(1)
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