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Old 09-15-2013, 01:37 AM   #1
fereshteh
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Registered: Jul 2013
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bash


hi all
i have seen one command line in my program's build.bash file. It is:
[code]if [ -n "${USE_PARALLEL_IO:+1}" ] && [ -n "${USE_MPI:+1}" ]; then if [ "${which_MPI}" = "mpich" ]; then ...
i want to know what is the meaning of && sign .
All the best
fereshte

Last edited by fereshteh; 09-15-2013 at 02:39 AM.
 
Old 09-15-2013, 01:48 AM   #2
jdkaye
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It marks an "and list" So
Code:
command1 && command2
means "execute command1 and then execute command2".
Example:
Code:
sudo aptitude update && sudo aptitude safe-upgrade
You can find all this and more in your favourite (and free) bash manual.
Enjoy
jdk

Last edited by jdkaye; 09-15-2013 at 02:44 AM.
 
Old 09-15-2013, 01:53 AM   #3
colucix
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Please take a look at the bash manual here: http://www.gnu.org/software/bash/man...ref.html#Lists
In your if/then construct, you can think at && as logical AND, that means the condition is true if both the expressions inside square brackets are true.
 
Old 09-15-2013, 02:44 AM   #4
fereshteh
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thanks

dear
many thanks for your reply and sending required link
cheers
fereshte
 
  


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