新建一个文件并让文件中显示行号方便后续执行查看结果

cat -b /etc/passwd > a.txt

cat /a.txt

   ......................省略N行

   34dhcpd:x:177:177:DHCP server:/:/sbin/nologin

    35lisi:x:500:500::/home/lisi:/bin/bash

    36zhangsan:x:501:501::/home/zhangsan:/bin/bash

    37mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash

    38named:x:25:25:Named:/var/named:/sbin/nologin

    39qemu:x:107:107:qemu user:/:/sbin/nologin

    40radvd:x:75:75:radvd user:/:/sbin/nologin

编写脚本

[root@svr5 桌面]# vim /shell/del.sh 

#!/bin/bash

lines=`cat $1 | wc -l`

sline=`expr $lines - 1`

sed -i  ''$sline',+1d'  $1

执行脚本

[root@svr5 桌面]# sh /shell/del.sh /a.txt 

查看执行结果

[root@svr5 桌面]# cat /a.txt

    .....................省略N行

    35lisi:x:500:500::/home/lisi:/bin/bash

    36zhangsan:x:501:501::/home/zhangsan:/bin/bash

    37mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash

    38named:x:25:25:Named:/var/named:/sbin/nologin