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copying a line from a file using sed

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# 1  
Old 08-06-2011
copying a line from a file using sed
Hi All,

I need to copy a specific line from a file to another file.
lets suppose the line number 13 of a file
when I am writing the line number explicitly.. its working fine
Code:
sed -n '13p' afile > anotherfile

but, when inside a script, i am getting the line number value inside a variable called line, i am not getting the expected result.

Code:
sed -n '$linep' afile > anotherfile

even I tried with
Code:
sed -n '"$line"p' afile > anotherfile

I am getting the error :
Code:
sed: "$line"p is not a recognized function.

Please help !!!
# 2  
Old 08-06-2011
Hi,

See next example:
Code:
$ cat infile
last name,first name,address,zip,telephone,year of birth
Appleby,Anne,Shrimpsbury,SH-124,555-4455,1960
Brown,Carl,Midsomer Garden,MD-945,555-2423,1982
Smith,John,Shrimpsbury,SH-123,555-4584,1978
Underwood,Mary,Oglsby,OG-345,555-3434,1956
$ cat script.sh
#!/usr/bin/env bash

line=3
sed -n "$line"'p' infile
$ bash script.sh
Brown,Carl,Midsomer Garden,MD-945,555-2423,1982

Regards,
Birei
# 3  
Old 08-06-2011
Oh Thanks Birei.. Believe, I have got it from your example.
I was using
Code:
sed -n '"$line"p' infile

rather, it should be
Code:
sed -n "$line"'p' infile

I am not with my system now. Will check and confirm later. Thanks for the help.
# 4  
Old 08-06-2011
Also works:
Code:
$ cat script.sh
#!/usr/bin/env bash                                                                                                                                                                                                                          
                                                                                                                                                                                                                                             
line=3                                                                                                                                                                                                                                       
sed -n "${line}p" infile
$ bash script.sh
Brown,Carl,Midsomer Garden,MD-945,555-2423,1982

Regards,
Birei
# 5  
Old 08-06-2011
Code:
line=13
sed -n ''$line'p' infile

Note: these are two single quotes followed by a $ and then word line

Code:
tmp>wc -l austa1106.002
3079 austa1106.002
tmp>sed -n '13 p' austa1106.002
LA999888
tmp>export myln=13
tmp>sed -n ''$myln' p' austa1106.002
LA999888
tmp>

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