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1 awk command

1 awk command

• Copy exercise files

[root@worker1 dir9]# cp /etc/passwd ./testpasswd

• Print the first field

[root@worker1 dir9]# head -n2 testpasswd | awk -F ':' '{print $1}'
ROOT
bin

• Print entire line

[root@worker1 dir9]# head -n2 testpasswd | awk -F ':' '{print $0}'
ROOT:x:0:0:roooot:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin

• Print the first field, the second field, the third field, the fourth field, the print separator is ""

[root@worker1 dir9]# awk -F ':' '{print $1"#"$2"#"$3"#"$4}' testpasswd
ROOT#x#0#0
bin#x#1#1
daemon#x#2#2
adm#x#3#4
lp#x#4#7
sync#x#5#0
shutdown#x#6#0
halt#x#7#0
mail#x#8#12
operator#x#11#0
games#x#12#100
ftp#x#14#50
nobody#x#99#99
avahi-autoipd#x#170#170
systemd-bus-proxy#x#999#997
systemd-network#x#998#996
dbus#x#81#81
polkitd#x#997#995
tss#x#59#59
postfix#x#89#89
sshd#x#74#74
user#x#1000#1000
user1#x#1001#1001
user2#x#1002#1100
user3#x#1111#1100
user5#x#1112#1112
user6#x#1113#1113
ntp#x#38#38
tcpdump#x#72#72
BUS123###

• Matching character "oo"

[root@worker1 dir9]# awk '/oo/' testpasswd
ROOT:x:0:0:roooot:/root:/bin/bash
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin

• The first field matches the character "adm"

[root@worker1 dir9]# awk -F ':' '$1 ~/adm/' testpasswd
adm:x:3:4:adm:/var/adm:/sbin/nologin

• Print the first field and the third field of the matching character "root"; print the first field, the third field and the fourth field of the matching character "adm"

[root@worker1 dir9]# awk -F ':' '/root/ {print $1,$3} /adm/ {print $1,$3,$4}' testpasswd
ROOT 0
adm 3 4
operator 11

• The third field is a line with a character value of 0

[root@worker1 dir9]# awk -F ':' '$3=="0"' testpasswd
ROOT:x:0:0:roooot:/root:/bin/bash

• Lines whose third field is greater than or equal to a character value of 500 (in ASCII code form)

[root@worker1 dir9]# awk -F ':' '$3>="500"' testpasswd
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
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin
systemd-network:x:998:996:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:997:995:User for polkitd:/:/sbin/nologin
tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin

• Lines with a value greater than or equal to 500 in the third field

[root@worker1 dir9]# awk -F ':' '$3>=500' testpasswd
systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin
systemd-network:x:998:996:systemd Network Management:/:/sbin/nologin
polkitd:x:997:995:User for polkitd:/:/sbin/nologin
user:x:1000:1000::/home/user:/bin/bash
user1:x:1001:1001::/home/user1:/bin/bash
user2:x:1002:1100::/home/user2:/bin/bash
user3:x:1111:1100::/home/user3:/bin/bash
user5:x:1112:1112::/home/user5:/bin/bash
user6:x:1113:1113::/home/user6:/bin/bash

• Lines with the seventh field value character "/sbin/nologin"

[root@worker1 dir9]# awk -F ":" '$7!="/sbin/nologin"' testpasswd
ROOT:x:0:0:roooot:/root:/bin/bash
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
user:x:1000:1000::/home/user:/bin/bash
user1:x:1001:1001::/home/user1:/bin/bash
user2:x:1002:1100::/home/user2:/bin/bash
user3:x:1111:1100::/home/user3:/bin/bash
user5:x:1112:1112::/home/user5:/bin/bash
user6:x:1113:1113::/home/user6:/bin/bash
BUS123

• Print rows with a fourth field larger than a third field

[root@worker1 dir9]# awk -F ":" '$3>$4' testpasswd
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
operator:x:11:0:operator:/root:/sbin/nologin
systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin
systemd-network:x:998:996:systemd Network Management:/:/sbin/nologin
polkitd:x:997:995:User for polkitd:/:/sbin/nologin
user3:x:1111:1100::/home/user3:/bin/bash

• Print lines with a third field larger than the fifth field and a third field larger than a character value of 7

[root@worker1 dir9]# awk -F ":" '$3>"5" && $3<"7"' testpasswd
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin

• Print a numeric value greater than 1000 in the third field or a row with the seventh field equal to the character "/bin/bash"

[root@worker1 dir9]# awk -F ":" '$3>1000||$7=="/bin/bash"' testpasswd
ROOT:x:0:0:roooot:/root:/bin/bash
user:x:1000:1000::/home/user:/bin/bash
user1:x:1001:1001::/home/user1:/bin/bash
user2:x:1002:1100::/home/user2:/bin/bash
user3:x:1111:1100::/home/user3:/bin/bash
user5:x:1112:1112::/home/user5:/bin/bash
user6:x:1113:1113::/home/user6:/bin/bash

• Print fields 1,3,4 with the spacer ""

[root@worker1 dir9]# head -5 testpasswd | awk -F ":" '{OFS="#"} {print $1,$3,$4}'
ROOT#0#0
bin#1#1
daemon#2#2
adm#3#4
lp#4#7

• Conditional Judgment: The third field is greater than 1000 values, print the first, third, and fourth fields, and the spacer is ""

[root@worker1 dir9]# awk -F ":" '{OFS="#"} { if($3>1000) {print $1,$3,$4}}' testpasswd
user1#1001#1001
user2#1002#1100
user3#1111#1100
user5#1112#1112
user6#1113#1113

• Print the number of fields separated by ":"

[root@worker1 dir9]# head -n5 testpasswd | awk -F ":" '{print NF}'
7
7
7
7
7

• Print line numbers separated by ":"

[root@worker1 dir9]# head -n5 testpasswd | awk -F ":" '{print NR}'
1
2
3
4
5

• Print lines with line numbers greater than 20

[root@worker1 dir9]# awk 'NR>20' testpasswd
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
user:x:1000:1000::/home/user:/bin/bash
user1:x:1001:1001::/home/user1:/bin/bash
user2:x:1002:1100::/home/user2:/bin/bash
user3:x:1111:1100::/home/user3:/bin/bash
user5:x:1112:1112::/home/user5:/bin/bash
user6:x:1113:1113::/home/user6:/bin/bash
ntp:x:38:38::/etc/ntp:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
BUS123

• Print lines with a line number less than 20 and match the character "roo"

[root@worker1 dir9]# awk 'NR<20 && $1 ~ /roo/' testpasswd
ROOT:x:0:0:roooot:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin

• Print the first field equal to the character "bin"

[root@worker1 dir9]# head -n3 testpasswd | awk -F ":" '$1=="bin"'
bin:x:1:1:bin:/bin:/sbin/nologin

• Calculate the sum of the third field

[root@worker1 dir9]# awk -F ':' '{sum=sum+$3} END {print sum}' testpasswd
10088

Conditional Matching: Print the line with the first field equal to the character "bin"

[root@worker1 dir9]# awk -F ':' '$1=="bin" {print $0}' testpasswd
bin:x:1:1:bin:/bin:/sbin/nologin

extend
Practice all exercises. http://www.apelearn.com/study_v2/chapter14.html