Extract a line from a file using the line number

zambo · #1 (**permalink**) 05-01-2008

I have a shell script and want to assign a value to a variable. The value is the line exctrated from a file using the line number. The line number it is not fix, and could change any time.
I have tried sed, awk, head .. See my script

# Get randome line number from the file
#selectedline = `awk 'NR==$randomline {print $0}' $filename`
#awk 'NR==$randomline {print $0}' $filename
selectedline=`sed -n "${randomline}{p;q;}" $filename`
#sed -n "${randomline}{p;q;}" $filename
#selectedline=`head -$randomline $filename |tail -1`
#head -${randomline} $filename |tail -1
echo "Random line = $selectedline"
The problem is that after getting the desired line specified by randomline, the entire file is expanded in the variable selectedline. This the case only ,when assigned to a variable.

Need help

jim mcnamara · #2 (**permalink**) 05-01-2008

Code:

# one way
lin=4
file=/path/somefile
sed -n $lin,"$lin"p $file | read myvariable
# another way
myvariable=`awk -v line=$lin "NR==line" $file`

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
extract a line from a file using the line number	grandtheftander	Shell Programming and Scripting	7	01-22-2009 10:24 AM
Using grep to extract line number	mskarica	Shell Programming and Scripting	8	06-26-2008 02:47 AM
Adding a columnfrom a specifit line number to a specific line number	Ezy	Shell Programming and Scripting	2	05-12-2008 08:29 AM
Appending the line number and a seperator to each line of a file ?	pjcwhite	Shell Programming and Scripting	4	03-21-2007 01:29 AM
Get line form file by line number	corny	Shell Programming and Scripting	3	08-25-2006 12:18 PM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:


	Powered by