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Having sed to read lines of a file with the use of a variable..Possible?

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# 1  
Old 08-19-2010
Tools Having sed to read lines of a file with the use of a variable..Possible?
This i will print the second line of a file
sed -n '2p' test2
The use of a variable is impossible here.
Code:
a=1
while [ X"$line" != X"" ]; do
line=`sed -n '$a p' test2`

# do some things here with the line variable
a=`expr $a + 1`
done

But the uotput of sed command is 'p'..... What can i do to use a variable here?Smilie
# 2  
Old 08-19-2010
Code:
 
     variable=$(sed -n "${n}p;${n}q"  somefile)
    # do something with variable

This is ineffcient in a loop.
Code:
  a=1
  while read line
  do
      if [[ "$line" = "X" ]] ; then
          break;
      fi
      a=$(( $a + 1 ))
  done < inputfilename
  echo "$(( $line - 1  ))  contains X"

This reads the file one time
This User Gave Thanks to jim mcnamara For This Post:
hakermania
# 3  
Old 08-19-2010
Really experts around here Smilie
Thz, the solution with sed worked perfectly Smilie
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