UNIX for Dummies Questions & Answers

#! /bin/sh

val=\
"a      b       c       trk_012345678"
echo "$val"
num=${val##*_}
rest=${val%$num}
final=`expr $num + 1 `
if [[ ${#num} > ${#final} ]] ; then
echo "$rest"0"$final"
else
echo "$rest$final"
fi ;

#! /bin/sh

while read val
do
echo "$val"
num=${val##*_}
rest=${val%$num}
final=`expr $num + 1 `
if [[ ${#num} > ${#final} ]] ; then
echo "$rest"0"$final" > test1
else
echo "$rest$final" test1
fi ;
done < test

$ cat test
a<tab>b<tab>c<tab>Trk_01234567

$ awk -F_ '{printf "%s_%0*d\n", $1, length($2), ++$2}' test > test1

$ cat test1
a<tab>b<tab>c<tab>Trk_01234568