核心思想：cut
关键词：head tail cut

#!/bin/bash
# get the information about /etc/passwd 	PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATHfile="/etc/passwd"
line=`wc -l $file | cut -d" " -f1`for I in `seq 1 $line`;douserid=`head -$I $file |tail -1| cut -d: -f3`username=`head -$I $file|tail -1 | cut -d: -f1`   echo "$userid -- $username "
done
echo "there are $line users"