shell常用命令——awk正则表达式

其他 2018-07-03 01:08:11 阅读次数: 0

一、简述

awk 处理机制 :awk 会逐行处理文本 , 支持在处理第一行之前做一些准备工作 , 以及在处理完最后一行做一些总结性质的工作
在命令格式上分别体现如下 :
BEGIN{}: 读入第一行文本之前执行 , 一般用来初始化操作
{}: 逐行处理,逐行读入文本执行相应的处理,是最常见的编辑指令快

END{}: 处理完最后一行文本之后执行 , 一般用来输出处理结果

二、awk基本用法

awk [-F|-f] 'BEGIN{}{command1; command2} END{}' file
[-F|-f]   大参数，-F指定分隔符，-f调用脚本
'  '          引用代码块
//           匹配代码块，可以是字符串或正则表达式
{}           命令代码块，包含一条或多条命令

；          多条命令使用分号分隔


awk -F ":" '{print $1}' passwd 以冒号为分隔符打印passwd的第一列

[root@desktop mnt]# awk -F ":" '{print $1}' passwd
root
bin
daemon
adm
lp
sync
shutdown
halt
mail
operator
games
ftp
nobody
dbus
polkitd
avahi
avahi-autoipd
rpc
rpcuser
nfsnobody
ovirtagent
postfix
sshd
chrony
student
usbmuxd
colord
abrt
libstoragemgmt
unbound
qemu
saslauth
ntp
rtkit
radvd
pulse
gdm
gnome-initial-setup
tcpdump
westos
test
user1
user2
user3
[root@desktop mnt]#

awk -F ":" 'BEGIN{print "name"}{print $1}' passwd  先打印name,然后以冒号为分隔符打印passwd的第一列

awk -F ":" 'BEGIN{print "name"}{print $1}' passwd
name
root
bin
daemon
adm
lp
sync
shutdown
halt
mail
operator
games
ftp
nobody
dbus
polkitd
avahi
avahi-autoipd
rpc
rpcuser
nfsnobody
ovirtagent
postfix
sshd
chrony
student
usbmuxd
colord
abrt
libstoragemgmt
unbound
qemu
saslauth
ntp
rtkit
radvd
pulse
gdm
gnome-initial-setup
tcpdump
westos
test
user1
user2
user3

awk -F ":" 'BEGIN{print "name"}{print $1}END{print "END"}' passwd  先打印name,然后以冒号为分隔符打印passwd的第一列，然后在尾行打印END

[root@desktop mnt]# awk -F ":" 'BEGIN{print "name"}{print $1}END{print "END"}' passwd
name
root
bin
daemon
adm
lp
sync
shutdown
halt
mail
operator
games
ftp
nobody
dbus
polkitd
avahi
avahi-autoipd
rpc
rpcuser
nfsnobody
ovirtagent
postfix
sshd
chrony
student
usbmuxd
colord
abrt
libstoragemgmt
unbound
qemu
saslauth
ntp
rtkit
radvd
pulse
gdm
gnome-initial-setup
tcpdump
westos
test
user1
user2
user3
END

awk -F ":" 'BEGIN{print "NAME"}{print NR}END{print "END"}' passwd  先打印NAME,然后打印passwd每行的行号，然后在尾行打印END

[root@desktop mnt]# awk -F ":" 'BEGIN{print "NAME"}{print NR}END{print "END"}' passwd
NAME
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
END

awk -F ":" 'BEGIN{print "NAME"}{print NR$1}END{print "END"}' passwd 先打印NAME,然后打印passwd每行的行号，以冒号为分隔符打印passwd的第一列，然后在尾行打印END

[root@desktop mnt]# awk -F ":" 'BEGIN{print "NAME"}{print NR$1}END{print "END"}' passwd
NAME
1root
2bin
3daemon
4adm
5lp
6sync
7shutdown
8halt
9mail
10operator
11games
12ftp
13nobody
14dbus
15polkitd
16avahi
17avahi-autoipd
18rpc
19rpcuser
20nfsnobody
21ovirtagent
22postfix
23sshd
24chrony
25student
26usbmuxd
27colord
28abrt
29libstoragemgmt
30unbound
31qemu
32saslauth
33ntp
34rtkit
35radvd
36pulse
37gdm
38gnome-initial-setup
39tcpdump
40westos
41test
42user1
43user2
44user3
END

awk 'BEGIN{print "NAME"}{print }END{print "END"}' passwd   先打印NAME,然后打印passwd每行，然后在尾行打印END

[root@desktop mnt]# awk 'BEGIN{print "NAME"}{print }END{print "END"}' passwd
NAME
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:998:User for polkitd:/:/sbin/nologin
avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin
avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin
rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin
rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin
nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin
ovirtagent:x:175:175:RHEV-M Guest Agent:/usr/share/ovirt-guest-agent:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
chrony:x:998:996::/var/lib/chrony:/sbin/nologin
student:x:1000:1000:Student User:/home/student:/bin/bash
usbmuxd:x:113:113:usbmuxd user:/:/sbin/nologin
colord:x:997:995:User for colord:/var/lib/colord:/sbin/nologin
abrt:x:173:173::/etc/abrt:/sbin/nologin
libstoragemgmt:x:996:994:daemon account for libstoragemgmt:/var/run/lsm:/sbin/nologin
unbound:x:995:993:Unbound DNS resolver:/etc/unbound:/sbin/nologin
qemu:x:107:107:qemu user:/:/sbin/nologin
saslauth:x:994:76:"Saslauthd user":/run/saslauthd:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin
rtkit:x:172:172:RealtimeKit:/proc:/sbin/nologin
radvd:x:75:75:radvd user:/:/sbin/nologin
pulse:x:171:171:PulseAudio System Daemon:/var/run/pulse:/sbin/nologin
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
gnome-initial-setup:x:993:991::/run/gnome-initial-setup/:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
westos:x:1001:1001::/home/westos:/bin/bash
test:x:1002:1002::/home/test:/bin/bash
user1:x:1003:1003::/home/user1:/bin/bash
user2:x:1004:1004::/home/user2:/bin/bash
user3:x:1005:1005::/home/user3:/bin/bash
END

awk 'BEGIN{print "NAME"}{print NR;print }END{print "END"}' passwd  先打印NAME,然后打印每行的行号，每行行号下面打印内容，然后在尾行打印END

[root@desktop mnt]# awk -F ":" 'BEGIN{print "NAME"}{print NR;print }END{print "END"}' passwd
NAME
1
root:x:0:0:root:/root:/bin/bash
2
bin:x:1:1:bin:/bin:/sbin/nologin
3
daemon:x:2:2:daemon:/sbin:/sbin/nologin
4
adm:x:3:4:adm:/var/adm:/sbin/nologin
5
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
6
sync:x:5:0:sync:/sbin:/bin/sync
7
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
8
halt:x:7:0:halt:/sbin:/sbin/halt
9
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
10
operator:x:11:0:operator:/root:/sbin/nologin
11
games:x:12:100:games:/usr/games:/sbin/nologin
12
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13
nobody:x:99:99:Nobody:/:/sbin/nologin
14
dbus:x:81:81:System message bus:/:/sbin/nologin
15
polkitd:x:999:998:User for polkitd:/:/sbin/nologin
16
avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin
17
avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin
18
rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin
19
rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin
20
nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin
21
ovirtagent:x:175:175:RHEV-M Guest Agent:/usr/share/ovirt-guest-agent:/sbin/nologin
22
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
23
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
24
chrony:x:998:996::/var/lib/chrony:/sbin/nologin
25
student:x:1000:1000:Student User:/home/student:/bin/bash
26
usbmuxd:x:113:113:usbmuxd user:/:/sbin/nologin
27
colord:x:997:995:User for colord:/var/lib/colord:/sbin/nologin
28
abrt:x:173:173::/etc/abrt:/sbin/nologin
29
libstoragemgmt:x:996:994:daemon account for libstoragemgmt:/var/run/lsm:/sbin/nologin
30
unbound:x:995:993:Unbound DNS resolver:/etc/unbound:/sbin/nologin
31
qemu:x:107:107:qemu user:/:/sbin/nologin
32
saslauth:x:994:76:"Saslauthd user":/run/saslauthd:/sbin/nologin
33
ntp:x:38:38::/etc/ntp:/sbin/nologin
34
rtkit:x:172:172:RealtimeKit:/proc:/sbin/nologin
35
radvd:x:75:75:radvd user:/:/sbin/nologin
36
pulse:x:171:171:PulseAudio System Daemon:/var/run/pulse:/sbin/nologin
37
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
38
gnome-initial-setup:x:993:991::/run/gnome-initial-setup/:/sbin/nologin
39
tcpdump:x:72:72::/:/sbin/nologin
40
westos:x:1001:1001::/home/westos:/bin/bash
41
test:x:1002:1002::/home/test:/bin/bash
42
user1:x:1003:1003::/home/user1:/bin/bash
43
user2:x:1004:1004::/home/user2:/bin/bash
44
user3:x:1005:1005::/home/user3:/bin/bash
END

显示ip

[root@desktop mnt]# ifconfig eth0 | awk '/inet/{print}'
        inet 172.25.254.166  netmask 255.255.255.0  broadcast 172.25.254.255
        inet6 fe80::5054:ff:fe00:420a  prefixlen 64  scopeid 0x20<link>
[root@desktop mnt]# ifconfig eth0 | awk '/inet\>/{print}'
        inet 172.25.254.166  netmask 255.255.255.0  broadcast 172.25.254.255
[root@desktop mnt]#

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