Problem in understanding export uses


 
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# 1  
Old 07-10-2012
Java Problem in understanding export uses

i am beginner in shell scripting.
not able to understand what below line will do.

Code:
PS1=${HOST:=Žuname -nŽ}"$ " ; export PS1 HOST

below is the script

Code:
#!/bin/hash
   
  PS1=${HOST:=Žuname -nŽ}"$ " ; export PS1 HOST ;
   
  echo $PS1

and i getting the below output

Code:
Žuname -nŽ$


Last edited by methyl; 07-10-2012 at 08:11 AM.. Reason: forgot to add script and the o/p
# 2  
Old 07-10-2012
you may use the man pages available!!

EXPORT
# 3  
Old 07-10-2012
hi PIKK45
what i understand from this is

here we are putting the o/p of host to PS1. not sure if i am rite or not but if this is the case the o/p should be the machine name .
but getting different o/p why ?
# 4  
Old 07-10-2012
You are using the wrong quotes.
Here is the correct way:
Code:
PS1=${HOST:=`uname -n`}"$ "

or better
Code:
PS1="${HOST:=$(uname -n)} $ "

# 5  
Old 07-10-2012
From what I understand,

You should be getting the O/P as your hostname or machine name whatever that you use.

Say, I am working on "Server X" and execute
Code:
uname -n

in command line I should get Server X as the output.

The same is applicable in this script also. But this is doing another work. Exporting the variables PS1 and HOST.

Note that, in my case PS1 will be ServerX$ and HOST would be Server X
# 6  
Old 07-10-2012
Hi PIKK45

not understand exactly .

you want to say that o/p of my script is correct
# 7  
Old 07-10-2012
Your script has errors. Please see jlliagre's post for the corretion.

And after correction,

uname -n ===> Gives you the hostname of the system you are working on. So,
Code:
HOST:=`uname -n`

will contain that hostname.

Now,
Code:
PS1=$(HOST:=`uname -n`)"$ "

means, you are adding an additional symbol $ to the end of the hostname and storing it in the variable PS1

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