cat & 文件结束符

语法：

　　连接显示

选项：

　　-n，显示行号。

　　-v，显示不可见打印符。

　　-E，显示“行结束符”（$）。

　　显示行号

$ cat -n /etc/fstab
       /dev/VolGroup00/LogVol00 /                       ext3    defaults
       LABEL=/boot             /boot                   ext3    defaults
       tmpfs                   /dev/shm                tmpfs   defaults
       devpts                  /dev/pts                devpts  gid=,mode=
       sysfs                   /sys                    sysfs   defaults
       proc                    /proc                   proc    defaults
       /dev/VolGroup00/LogVol01 swap                    swap    defaults         

　　打印行末结束符

$ cat -E /etc/fstab
/dev/VolGroup00/LogVol00 /                       ext3    defaults         $
LABEL=/boot             /boot                   ext3    defaults         $
tmpfs                   /dev/shm                tmpfs   defaults         $
devpts                  /dev/pts                devpts  gid=,mode=   $
sysfs                   /sys                    sysfs   defaults         $
proc                    /proc                   proc    defaults         $
/dev/VolGroup00/LogVol01 swap                    swap    defaults         $

　　直接输入命令，就会进入交互模式。直到cat接到一个“文件结束符”时停止交互。

$ cat
hello
hello
are you busy?
are you busy?
$

　　重写程序（case语句的第一个例子“找工作时联系人信息”），使用“文件结束符”，格式化显示交互信息：

#!/bin/bash

cat << EOF
Recruitment Announcement
  Are you ready to apply for any job?
     accounting
     cashier
     secretary
Please enter a number to select the corresponding positions.
EOF

echo -n "Choice: "
read NUM
case $NUM in
  )
    printf "call mr wang. number is 1124\n"
    ;;
  )
    printf "call miss li. number is 1233.\n"
    ;;
  )
    printf "call miss ji. number is 1367.\n"
    ;;
  *)
    printf "If you want to make a lot of money, to be a seller. call 1498.\n"
    ;;
esac

　　打印程序的提示信息：

display_help () {
    cat << EOF
Usage: findTom [OPTION]
View the tomcat information.
View the home directory of the tomcat program running on the system, and
the project path. 

Mandatory arguments to long option are mandatory for short options too.
  -r, --read
      view the previously running tomcat information.
  -v, --version
      view the version
  --clear
      when the number of row is greater than , then clean-up, and leaving  lines.
  -h, --help
      display this help and exit

E-mail bug reports to: <@qq.com>
EOF
}

执行上边的代码，效果如下：

$ ./cat.sh
Recruitment Announcement
  Are you ready to apply for any job?
     accounting
     cashier
     secretary
Please enter a number to select the corresponding positions.
Choice:

　　从程序的输出看出，脚本里的文本格式原样在交互界面显示了。

---

文件结束符：

　　Linux: CTRL + d

　　Windows: CTRL + z