Shell Programming and Scripting

while read line ; do
        single_char=`???`
        echo "$single_char"
done < $input_file

fdgfdgfdg
gegthhy
mjtumjuymy
uymyfyjhr
trjhryh

cut -c 3-6 inputfile

gfd
gth
tum
myf
jhr

while read line ; do
        k=`echo $line|cut -c 26`
        if [ $k = "X" ] ; then
                echo "Character at the row was X"
        fi
done < $input_file

while read line ; do
        k=`echo "${line}"|cut -c 26`
        if [ "${k}" = "X" ] ; then
                echo "Character at the row was X"
        fi
done < $input_file

while read line; do
  echo "${line:25:1}"
done

$ time ./read_line_do.sh infile > /dev/null
real	0m18.873s
user	0m18.285s
sys	0m0.580s

$ time gawk '{print substr($0,25,1)}' infile > /dev/null
real	0m3.884s
user	0m3.860s
sys	0m0.024s

$ time original-awk '{print substr($0,25,1)}' f > /dev/null
real	0m1.244s
user	0m1.224s
sys	0m0.020s

$ time mawk '{print substr($0,25,1)}' infile > /dev/null
real	0m0.111s
user	0m0.084s
sys	0m0.028s