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using sed to replace values...

 
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# 1  
Old 09-02-2009
using sed to replace values...
I have a file:

Code:
$somevar=somevalue
$anothervar=
$someothervar=45

I'd like to be able to replace the values in the file. I just don't know how exactly to use sed. I was thinking along the lines of:

Code:
cat file | sed "s/$somevar=/anotherval/g"

I was hoping this would make the file:

Code:
$somevar=anotherval
$anothervar=
$someothervar=45


The thing is, I don't know what the values will be in this file. I wish I knew regular expressions and sed fully, but I don't.
# 2  
Old 09-03-2009
Code:
sed 's/serach_pattern/replace_pattern/g' filename

this will print the result on stdout.

Code:
sed 's/serach_pattern/replace_pattern/g' filename > tmp;mv tmp filename

will make the changes in file.
# 3  
Old 09-03-2009
If am not wrong, then the following is what you want.

Code:
sed 's/$somevar=.*$/$somevar=anotherval/' t1

To edit that file itself. ( but be careful )..
Code:
sed -i 's/$somevar=.*$/$somevar=anotherval/' t1

 
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