Sed 行編輯器
sed（stream editor）：
- 用來操作純 ASCII 碼的文本
-
Sed 一次處理一行内容
處理時，把目前處理的行存儲在臨時緩沖區中，稱之為“模式空間”（pattern space）
- 可以指定僅僅處理哪些行，Sed 符合模式條件的處理，不符合條件的不予處理
- 處理完成之後把緩沖區的内容送往螢幕
- 接着處理下一行,這樣不斷重複,直到檔案末尾
sed指令格式
sed [參數] ‘指令’ file
Sed 對字元的處理
p ##顯示，将某個選擇的資料列印顯示。通常 p 會與參數 sed -n 一起執行
d ##删除，顯示模式空間删除指定行後的内容，不會對原檔案資料删除
a ##添加，a 的後面可以接字元串，該字元串會在目前指定行的下一行出現
c ##更改， c 的後面可以接字元串，該字元串可以取代 n1,n2 之間的行
i ##插入， i 的後面可以接字元串，該字元串會在目前指定行的上一行出現
p
[[email protected] mnt]# cat -n /etc/fstab
1
2 #
3 # /etc/fstab
4 # Created by anaconda on Sun Sep 23 22:41:24 2018
5 #
6 # Accessible filesystems, by reference, are maintained under '/dev/disk'
7 # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
8 #
9 /dev/mapper/rhel_foundation63-root / xfs defaults 0 0
10 UUID=9bbad413-0771-45fc-9ddb-fd2ba6994561 /boot xfs defaults 0 0
11 UUID=A5EB-573A /boot/efi vfat umask=0077,shortname=winnt 0 0
12 /dev/mapper/rhel_foundation63-swap swap swap defaults 0 0
[[email protected] mnt]# sed -n '/\:/p' /etc/fstab
# Created by anaconda on Sun Sep 23 22:41:24 2018
[[email protected] mnt]# sed -n '/^#/p' /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sun Sep 23 22:41:24 2018
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
[[email protected] mnt]# sed -n '/^#/!p' /etc/fstab
/dev/mapper/rhel_foundation63-root / xfs defaults 0 0
UUID=9bbad413-0771-45fc-9ddb-fd2ba6994561 /boot xfs defaults 0 0
UUID=A5EB-573A /boot/efi vfat umask=0077,shortname=winnt 0 0
/dev/mapper/rhel_foundation63-swap swap swap defaults 0 0
[[email protected] mnt]# sed -n '2,6p' /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sun Sep 23 22:41:24 2018
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
[[email protected] mnt]# sed -n '2p;6p' /etc/fstab
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
d
[[email protected] mnt]# sed '/^UUID/d' fstab
#
# /etc/fstab
# Created by anaconda on Sun Sep 23 22:41:24 2018
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/rhel_foundation63-root / xfs defaults 0 0
/dev/mapper/rhel_foundation63-swap swap swap defaults 0 0
[[email protected] mnt]# sed '/^#/d' fstab
/dev/mapper/rhel_foundation63-root / xfs defaults 0 0
UUID=9bbad413-0771-45fc-9ddb-fd2ba6994561 /boot xfs defaults 0 0
UUID=A5EB-573A /boot/efi vfat umask=0077,shortname=winnt 0 0
/dev/mapper/rhel_foundation63-swap swap swap defaults 0 0
[[email protected] mnt]# sed '/^$/d' fstab
#
# /etc/fstab
# Created by anaconda on Sun Sep 23 22:41:24 2018
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/rhel_foundation63-root / xfs defaults 0 0
UUID=9bbad413-0771-45fc-9ddb-fd2ba6994561 /boot xfs defaults 0 0
UUID=A5EB-573A /boot/efi vfat umask=0077,shortname=winnt 0 0
/dev/mapper/rhel_foundation63-swap swap swap defaults 0 0
[[email protected] mnt]# sed '1,4d' fstab
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/rhel_foundation63-root / xfs defaults 0 0
UUID=9bbad413-0771-45fc-9ddb-fd2ba6994561 /boot xfs defaults 0 0
UUID=A5EB-573A /boot/efi vfat umask=0077,shortname=winnt 0 0
/dev/mapper/rhel_foundation63-swap swap swap defaults 0 0
a
[[email protected] mnt]# cat hello.sh
hello
[[email protected] mnt]# sed '/hello/aworld' hello.sh
hello
world
[[email protected] mnt]# sed 's/hello/hello world/g' hello.sh
hello world
[[email protected] mnt]#
[[email protected] mnt]# sed 's/hello/hello\nworld/g' hello.sh
hello
world
c
[[email protected] mnt]# sed '/hello/chello world' hello.sh
hello world
i
[[email protected] mnt]# sed '/hello/iworld\nwestos' hello.sh
world
westos
hello
練習：
将httpd服務的端口80改為8080
#!/bin/bash
yum install httpd -y $> /dev/null
sed -i "/^Listen/cListen $1" /dev/httpd/conf/httpd.conf
echo -e "Port has changed!"
echo "Now,port is $1!"
ststemctl restart httpd
~