1. Find the IPV4 address of this machine in Ifconfig "NIC name" command result
Ifconfig | Head-n 2 |tail-1 |tr-s "" |cut-d ""-f3
2. Find out the maximum percentage value of partition space utilization
DF |tr-s "" |cut-d ""-f5
3, identify the user UID maximum user name, UID and shell type
cat/etc/passwd | Cut-d:-f1,3,7| Sort-nt:-k2 |tail-n 1
4. Find out the permissions of/tmp and display them digitally
stat/tmp | Head-n 4 |tail-n 1|cut-c10-13
5. Count the number of connections for each remote host IP currently connected to this machine, and sort from large to small (no image)
Cat/var/log/httpd/access_log |cut-d ""-f1 |sort |uniq-c |sort-n-R |head
6. A line that displays at least one whitespace character in the CentOS7/etc/grub2.cfg file, followed by a non-whitespace character
grep "^[[:blank:]]+"/etc/grub2.cfg |grep-v "^[[:space:]
$"
7. Find the line that ends with ' LISTEN ' followed by any number of whitespace characters in the result of the "Netstat-tan" command
Netstat-tan |grep "Listen[[:blank:]$"
8. Display user name and UID of all system users on CentOS7
CAT/ETC/PASSWD |cut-d:-f1,3 | Egrep-v "[0-9]{4,}"
9, add user Bash, Testbash, basher, SH, nologin (its shell is/sbin/nologin), find the/etc/passwd user name with the shell name of the line
grep "(^.
) \>.\<\1$ "/etc/passwd
10, take advantage of DF and grep, remove the disk partition utilization, and from large to small sort
DF |egrep "\<[0-9]
%."-o|sort-nr
11. Display three user root, Mage, Wang Uid and default shell (C7 instead)
CAT/ETC/PASSWD |egrep "^ (root| C7) "|cut-d:-f1,3
12. Find the line at the beginning of the/etc/rc.d/init.d/functions file that has a word (including an underscore) followed by a parenthesis
Egrep ".
() "/etc/rc.d/init.d/functions
13. Use Egrep to remove the base name from the/etc/rc.d/init.d/functions (make a little speculative suspicion)
echo/etc/rc.d/init.d/functions | Egrep "[A-z]$"
14. Use Egrep to remove the directory name of the path above
echo/etc/rc.d/init.d/functions | Egrep "/.*/"
15. Count the number of logins per host IP address that was logged in as root in the last command
last|cut-c23-38 |sort|uniq-c|sort-rn|head-n 1
16. Use extended regular expressions to represent 0-9, 10-99, 100-199, 200-249, 250-255, respectively
echo {1..255} |
Egrep "\<[0-9]\>"
Egrep "\<1[0-9]\>"
Egrep "\<1[0-9][0-9]\>"
Egrep "\<2[0-4][0-9]\>"
Egrep "\<25[0-5]\>"
17. Display all IPV4 addresses in ifconfig command result (write blindly)
Ifconfig |egrep "[0-9]{1,3}. [0-9] {1,3}. [0-9] {1,3}. [0-9] {1,3} "
18, this string: Welcome to Tiantianpaokuzhentmdehaowan each character in Linux to go to the weight and sort, repeat the number of rows to the front
echo Wecomele to Tiantianpaokuzhentmdehaowan Linux |grep-o. |sort |uniq-c |sort-nr
If there is any mistake, please criticize it.
The practice collection of regular expressions in Linux
