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grep a part of a line

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# 1  
Old 08-22-2008
grep a part of a line
Hi,

In a file FILE, there is a line like this one

MOLECULE C2 H2

I want to extract "C2 H2". I can do it in two step in a script :
Code:
VARIABLE="`grep MOLECULE FILE`" # Assign "MOLECULE C2 H2"
VARIABLE=`echo ${VARIABLE/"MOLECULE "}` # Remove "MOLECULE ".

Then,
Code:
$echo $VARIABLE

gives
C2 H2

Is anyone know how to do it in a more straightforward way?

Thanks a lot,
Tipi
Last edited by Yogesh Sawant; 07-22-2011 at 05:48 AM.. Reason: added code tags
# 2  
Old 08-22-2008
Code:
VARIABLE="`grep MOLECULE < FILE | sed 's/^MOLECULE //'`"

should do it.
Last edited by Yogesh Sawant; 07-22-2011 at 05:48 AM.. Reason: added code tags
# 3  
Old 08-22-2008
Maybe this :

grep MOLECULE FILE | cut [some options]

?
# 4  
Old 08-22-2008
Quote:
Originally Posted by Danny.Chouinard
VARIABLE="`grep MOLECULE < FILE | sed 's/^MOLECULE //'`"

should do it.
Yes, that work fine!

I have a lot of variables to read from files, all of them will be defined in the same way :

VARIABLE [ white space ] [ value to be assign ]

Is your little script the best way to do it efficiently?

Thanks a lot for you answer,

Tipi
# 5  
Old 08-22-2008
Another way...
Code:
VARIABLE=$(cut -d ' ' -f2- file)

# 6  
Old 08-22-2008
Quote:
Originally Posted by shamrock
Another way...
Code:
VARIABLE=$(cut -d ' ' -f2- file)

Yeah, but I have more than one variable in the files :

MOLECULE C2 H2
ECUT 30
etc...

and your script return (I think) the whole second column(?)

Thanks for your help!

Tipi
# 7  
Old 08-22-2008
Here's a way to process more than one variable at a time:

Code:
file=somefile
varlist="MOLECULE ECUT"
for var in $varlist ; do
  val="`grep \"^$var \" < $file | sed \"s/^$var //\"`"
  eval "${var}=\"${val}\""
done
echo "Molecule=$MOLECULE"
echo "Ecut=$ECUT"

Last edited by Yogesh Sawant; 07-22-2011 at 05:49 AM.. Reason: added code tags
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