awk
FS:输入字段分隔符
OFS:输出字段分隔符
RS:输入时的换行符
ORS:输出的换行符
NF:字段数量
$NF:最后一个字段
NR:统计行数
FNR:各个文件的行数统计
FILENAME:当前处理的文件名路径
ARGC:命令行参数的个数
ARGV:数组,以ARGV($1,...)调用
1.[root@localhost ~]# awk -v FS=":" '{print $1}' /etc/passwd
[root@localhost ~]# awk '{print $1}' /etc/passwd
[root@localhost ~]# gawk -v FS=":" '{print $1}' /etc/passwd相当于[root@localhost ~]# gawk -F: '{print $1}' /etc/passwd
[root@localhost ~]# awk -v FS=":" '{print $1,$3,$7}' /etc/passwd
[root@localhost ~]# awk -v FS=':' '{print $1,$3,$7}' /etc/passwd
[root@localhost ~]# awk -v FS=':' -v OFS='#' '{print $1,$3,$7}' /etc/passwd
[root@localhost ~]# awk -v RS=':' -v ORS='#' '{print}' /etc/passwd
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
[root@localhost ~]# awk '{print NF}' /etc/fstab 统计行字段个数;
[root@localhost ~]# awk '{print $NF}' /etc/fstab cat /etc/fstab 显示最后一个字段
[root@localhost ~]# awk 'BEGIN{print ARGC}' /etc/fstab /etc/issue
3
[root@localhost ~]# awk 'BEGIN{print ARGV[0]}' /etc/fstab /etc/issue
awk
[root@localhost ~]# awk -v test='glq hello' '{print test,$1}' /etc/fstab
glq hello
glq hello #
glq hello #
glq hello #
[root@localhost ~]# awk 'BEGIN{test="welcome";print test,$2}' /etc/fstab
welcome
[root@localhost ~]# awk -v test='to my log' '{print test,$2}' /etc/fstab
to my log
to my log
to my log /etc/fstab
to my log Created
to my log
to my log Accessible
[root@localhost ~]# awk -F: -v test="my log" '{print test,$7}' /etc/passwd
my log /bin/bash
my log /sbin/nologin
my log /sbin/nologin
----------------------------
printf
[root@localhost ~]# awk -F: '{printf "username: %-15s,UID: %d\n",$1,$3}' /etc/passwd
username: root ,UID: 0
username: bin ,UID: 1
username: daemon ,UID: 2
username: adm ,UID: 3
[root@localhost ~]# awk -F: '{printf "username: %-10s,UID: %-1d, Shell: %s\n",$1,$3,$7}' /etc/passwd
username: root ,UID: 0, Shell: /bin/bash
username: bin ,UID: 1, Shell: /sbin/nologin
username: daemon ,UID: 2, Shell: /sbin/nologin
[root@localhost ~]# awk -F: '{printf "username: %-10s UID: %-1d Shell: %s\n",$1,$3,$7}' /etc/passwd
username: root UID: 0 Shell: /bin/bash
username: bin UID: 1 Shell: /sbin/nologin
username: daemon UID: 2 Shell: /sbin/nologin
if判断语句:
[root@localhost ~]# awk -F: '{$3>=1000?usertype="common user":usertype="system user";printf "%15s:%-s\n",$1,usertype}' /etc/passwd
root:system user
bin:system user
daemon:system user
adm:system user
---------------------------------------
[root@localhost ~]# awk '/^UUID/{print $1}' /etc/fstab
UUID=63539c8b-2d17-4c5e-aa11-e232515bba61
[root@localhost ~]# awk '!/^UUID/{print $1}' /etc/fstab
#
#
#
#
#
#
#
/dev/mapper/centos-root
/dev/mapper/centos-swap
[root@localhost ~]# awk -F: '$3<1000{print "user:"$1,$3}' /etc/passwd
user:root 0
user:bin 1
user:daemon 2
user:adm 3
user:lp 4
user:sync 5
[root@localhost ~]# awk -F: '$NF=="/bin/bash"{print $1,$NF}' /etc/passwd
root /bin/bash
testdb /bin/bash
test1 /bin/bash
[root@localhost ~]# awk -F: '$NF~/bash$/{print $1,$NF}' /etc/passwd
root /bin/bash
testdb /bin/bash
test1 /bin/bash
[root@localhost ~]# awk -F: '/^root/,/^ftp/{print $1}' /etc/passwd
root
bin
daemon
adm
lp
sync
shutdown
halt
mail
operator
games
ftp
[root@localhost ~]# awk -F: '(NR>2&&NR<=10){print $1}' /etc/passwd
daemon
adm
lp
sync
shutdown
halt
mail
operator
BEGIN和END使用:
[root@localhost ~]# awk -F: 'BEGIN{print "username UID \n------------------------"}{printf "%-21s %s\n",$1,$3}' /etc/passwd
username UID
------------------------
root 0
bin 1
daemon 2
adm 3
lp 4
sync 5
shutdown 6
halt 7
mail 8
operator 11
games 12
ftp 14
nobody 99
avahi-autoipd 170
systemd-bus-proxy 999
systemd-network 998
dbus 81
polkitd 997
tss 59
postfix 89
sshd 74
mysql 27
testdb 1000
test1 1001
[root@localhost ~]# awk -F: 'BEGIN{print "username UID \n------------------------"}{printf "%-21s %s\n",$1,$3}END{print "end \n----------------------"}' /etc/passwd
username UID
------------------------
root 0
bin 1
daemon 2
adm 3
lp 4
sync 5
shutdown 6
halt 7
mail 8
operator 11
games 12
ftp 14
nobody 99
avahi-autoipd 170
systemd-bus-proxy 999
systemd-network 998
dbus 81
polkitd 997
tss 59
postfix 89
sshd 74
mysql 27
testdb 1000
test1 1001
end
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