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Vieri
Apprentice
Joined: 18 Dec 2005
Posts: 232
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 Posted: Thu Oct 16, 2008 9:10 pm Post subject: [SOLVED] simple bash logic question |
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Not strictly Gentoo-related but I'm wondering if someone could enlighten me on this.
I'd like to understand how "grouped conditions" work in bash. When I run the following code and the mount point doesn't exist, it runs the commands wthin || (). So, "error" is echoed out as expected. However, "continue" is also printed and if I check $? after the run I get 0.
Why doesn't the script "exit" with status 1 on the first line, within || () ?
The only way I found this to work as I want it to is by using the last lines I commented out.
Bash code:
| Code: |
#!/bin/bash
mount /furnstugurn || (echo "error"; exit 1)
echo "continue"
exit 0
#if [ $? -ne 0 ]; then
# echo "error"; exit 1
#fi
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Thanks in advance,
Vieri
Last edited by Vieri on Thu Oct 16, 2008 10:48 pm; edited 1 time in total |
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yabbadabbadont
Advocate
Joined: 14 Mar 2003
Posts: 4790
Location: 2 exits past crazy
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| Posted: Thu Oct 16, 2008 9:18 pm Post subject: |
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| By placing the echo and exit within parends (), you are running those commands within a sub-process that will "exit 1". Because it is a sub-process, it doesn't affect the main process. |
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Vieri
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Joined: 18 Dec 2005
Posts: 232
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| Posted: Thu Oct 16, 2008 10:48 pm Post subject: |
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| Thanks! |
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elzbal
Guru
Joined: 31 Aug 2002
Posts: 364
Location: Seattle, WA, USA
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| Posted: Mon Oct 20, 2008 3:07 am Post subject: |
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Just a reference note for future readers of this thread...
See also "man bash". Look at the "Shell Grammar" section, specifically the sections on "Compound Commands" and "Lists". There's a bit more information there about this. |
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