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Shell Programming and Scripting

replacing line with variable

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# 1  
Old 07-16-2009
replacing line with variable
All I want to do is replace the 2nd line in a file with a variable, eg,

var=xxx

the file 'test' containing:
aaa
bbb
ccc

replace bbb with xxx

aaa
xxx
ccc

I had it working with sed on a redhat machine, but it doesn't work on a mac machine.
# 2  
Old 07-17-2009
you can use sed or awk...
Code:
awk -v var="$your_var" 'NR==2{gsub($0,var)}{print}' filename

# 3  
Old 07-17-2009
Quote:
Originally Posted by vidyadhar85
you can use sed or awk...
Code:
awk -v var="$your_var" 'NR==2{gsub($0,var)}{print}' filename

That is just writing to standard out, not editing the actual file. I could redirect and mv it, but the files are large and I'd like to avoid having to do that.
# 4  
Old 07-17-2009
Quote:
Originally Posted by sideways
That is just writing to standard out, not editing the actual file. I could redirect and mv it, but the files are large and I'd like to avoid having to do that.
can be achieved using a tee
Code:
awk '{.....}' filename | tee filename

# 5  
Old 07-17-2009
I don't have much idea on "perl"..check for more options on editing on a particular line .

This might help you for inline coding

Code:
perl -i -pe 's/bbb/xxx/i;' file_name.txt



---------- Post updated at 10:07 PM ---------- Previous update was at 10:04 PM ----------

Good Rakesh ... I was thinking there will be some alternative to "perl"..since i prefer to do it in awk Smilie
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