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Shell Programming and Scripting

Switching between shells

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Top Forums Shell Programming and Scripting Switching between shells
# 1  
Old 05-05-2011
Lightbulb Switching between shells
I don't know why, but it just isn't working how I want it to work. You might want to run it to see what I mean. Or you might be a genius (or just really good at unix) and know just by looking at it what the problem is. Have fun trying to figure this one out.Smilie

Quote:
#!/bin/bash

Clear
echo ".-----------------------------------------------------------------."
echo "| |"
echo "| Please specify which Shell you want to switch to: |"
echo "| 1. Bash |"
echo "| 2. Korn Shell |"
echo "| 3. T Shell |"
echo "| |"
echo "'-----------------------------------------------------------------'"
echo " "
echo "Enter the number of your choice: "; read shell

case $shell in
1) echo "You are now in Bash"; `bash` ;;
2) echo "You are now in Korn shell"; `ksh` ;;
3) echo "You are now in T Shell"; `tcsh` ;;
esac
clear
# 2  
Old 05-06-2011
what do you mean its not working? Post the error and the expected behavior.
# 3  
Old 05-06-2011
tcsh wasn't working, but now I think I got it working. for some reason I had to execute the file directly, just typing tcsh didn't work for me here is the new script.

Quote:
#!/bin/bash

Clear
echo ".-----------------------------------------------------------------."
echo "| |"
echo "| Please specify which Shell you want to switch to: |"
echo "| 1. Bash |"
echo "| 2. Korn Shell |"
echo "| 3. T Shell |"
echo "| |"
echo "'-----------------------------------------------------------------'"
echo " "
echo "Enter the number of your choice: "; read shell

case $shell in
1) echo "Starting Bash..."; sleep 2; clear; `bash`;;
2) echo "Starting shell..."; sleep 2; clear; `ksh`;;
3) echo "Starting T Shell..."; sleep 2; clear; exec /bin/tcsh -l;;
esac
# 4  
Old 05-06-2011
There's no point to putting bash or ksh in backticks. And exec always has the side-effect of annihilating the program that runs it. Which is fine if that's the last thing your program ever does anyway, but then, why not do it for all options?
This User Gave Thanks to Corona688 For This Post:
nowruzr
# 5  
Old 05-07-2011
It is because bash and kcsh open just fine when I put them the way they are, but tcsh just doesn't open the right way. But the program is working, so I am just going to leave it alone until it starts causing me problems. then I just make them all open with exec
# 6  
Old 05-09-2011
I mean that putting them in backticks may have negative side-effects. Do you truly want to capture their output and turn it into an argument? If not, there's no point using backticks and doing so may cause errors later when arguments pop up in places you didn't want them.
# 7  
Old 05-09-2011
Oh ok so basically for the most part backticks are not required. But for some reason, I remember when I was writing another program, I had to put the backticks in or it just wasn't working. Is there a scenario where backticks are required?
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