Linux.com :: Command not executing from shell variable

Author	Message
supratik Joined: Apr 10, 2008 Posts: 9 Other Topics	Posted Apr 10, 2008 at 4:07:01 PM Subject: Command not executing from shell variable Hi All ! I am using Fedora 8, I tried to store a linux command into a shell variable and tried to execute that from the script. The code i have written is test="dialog --title \"MONyog Build Utility\" --backtitle \"MONyog Build Script\" --infobox \"hello world\" 16 20" bash "$test" but I am getting an error saying "No such file or directory". If i copy the same text and execute from the $prompt I am able to view the dialog box, the only problem is when I am trying to execute it from the script. I am not able to trace where I am missing in the code, so can anyone please help me!! Thanks Supratik
Back to top
Shashank Sharma Joined Jan 01, 1970 Posts: 1657 Location:New Delhi, India Other Topics	Posted: Apr 13, 2008 7:35:20 PM Subject: Command not executing from shell variable Maybe you should read some BASH tutorials and get a hang of shell variables: http://www.hypexr.org/bash_tutorial.php http://tldp.org/LDP/abs/html/ http://www.linuxtutorialblog.com/post/tutorial-the-best-tips-tricks-for-bash http://csdir.org/tutorials/bash-tutorial/ Coauthor of Beginning Fedora: From Novice to Professional published by Apress. Please follow the Forum Guidelines
Back to top
anup Joined Apr 05, 2008 Posts: 5 Other Topics	Posted: Apr 14, 2008 12:57:31 PM Subject: Command not executing from shell variable Check the permission given to the script,if it is only -rw-r--r-- then script will not work. use chmod 755 script_name then execute ./script_name While executing script the script should be in pwd.
Back to top
supratik Joined Apr 10, 2008 Posts: 9 Other Topics	Posted: Apr 14, 2008 7:47:22 PM Subject: Re: Command not executing from shell variable I have given the execution permission to the script. but still the problem persists in the script If I include the following two lines in the code, it works, cmd="ls -l" $cmd but it is not working for the same type of statements test="dialog --title \"MONyog Build Utility\" --backtitle \"MONyog Build Script\" --infobox \"hello world\" 16 20" $test The following error it thows Error: Unknown option Build. Use --help to list options. Please help me ! Regards Supratik
Back to top
griff5w Joined Aug 02, 2007 Posts: 1 Other Topics	Posted: Apr 18, 2008 2:46:37 PM Subject: Re: Command not executing from shell variable spuratik: Without seeing the 'Big Picture' I am not sure why you are putting the dialog into a variable as opposed to a function. What are you trying to accomplish by using a variable instead of a function? griff5w
Back to top
Peter Jakobi Joined Jun 21, 2007 Posts: 7 Other Topics	Posted: Apr 18, 2008 4:22:33 PM Subject: Re: Re: Re: Re: Re: Re: Command not executing from she [quote=supratik] I am using Fedora 8, I tried to store a linux command into a shell variable and tried to execute that from the script. The code i have written is test="dialog --title \"MONyog Build Utility\" --backtitle \"MONyog Build Script\" --infobox \"hello world\" 16 20" bash "$test" [/quote] First simplify and try some variants: D='dialog --title x --backtitle y --infobox z 16 10'; $D # ok D='dialog --title "x z" --backtitle y --infobox z 16 10'; $D # bug Strange, isn't it? Well, welcome and enjoy your visit to the Quoting $Hell: The problem is the way word splitting and variable expansion is performed by the shell. Work arounds are: a) use perl (python, ruby) with saner quotation and the ability to safely pass arrays to system/exec (e.g. system @command;). b) D='dialog --title "x z" --backtitle y --infobox z 16 10'; eval $D. --------------- ^^^^^ you want to (re)parse/split because of "x z" For more info, check man bash or one of the better korn shell books. [Modified by: Peter Jakobi on April 18, 2008 05:34 PM] [Modified by: Peter Jakobi on April 18, 2008 05:35 PM]
Back to top
Shashank Sharma Joined Jan 01, 1970 Posts: 1657 Location:New Delhi, India Other Topics	Posted: Apr 18, 2008 5:40:18 PM Subject: Command not executing from shell variable First of all, you don't need to escape where you have in your script. This works perfectly: test="dialog --title "MONyog" --backtitle "MONyog" --infobox "hello" 16 20" $test The above works without any problems. For some reason, when you use a variable, you can't use more than one word for the title, backtitle and infobox. As a command on BASH, you can do: dialog --title "MONyog Build Utility" --backtitle "MONyog Build Script" --infobox "hello world" 16 20 and there wouldn't be any problem. But in a variable, like you're trying to do, you can't use spaces and more than one word. So, I tried to escape the spaces, like so: test="dialog --title "MONyog\ Build" --backtitle "MONyog" --infobox "hello\ world" 16 20" $test But this doesn't work either. You just need to figure out a way to handle multiple letters and spaces with variable in a shell script and that will solve the problem. Coauthor of Beginning Fedora: From Novice to Professional published by Apress. Please follow the Forum Guidelines
Back to top
Anand Joined Apr 18, 2008 Posts: 1 Other Topics	Posted: Apr 18, 2008 7:42:41 PM Subject: Re: Command not executing from shell variable This one seems to work: TEST="dialog --title \"MONyog Build Utility\" --backtitle \"MONyog Build Script\" --infobox \"hello world\" 16 20" eval $TEST
Back to top
supratik Joined Apr 10, 2008 Posts: 9 Other Topics	Posted: Apr 19, 2008 7:02:23 PM Subject: Command not executing from shell variable Hi ! Thanks guys. It worked, i tried with what every one has suggested. Thanks once again. ------------------------- Regards Supratik
Back to top