Top 50 Linux Interview Questions and Answers for Devops
Top 50 Linux Interview Questions and Answers for DevOps
in this article i am going to explain top 50 interview question and answers for devops. These questions and answers are very useful in realtime projects.
1) How to find the files containing particular string
using grep command we can find the files containing particular string
grep -rl “string” <path>
grep -rl "devops" ./abcd ./abcd/hello.txt ./abcd/tt/sf.txt
-l represents show the file name not the lines
-r represents recursive search.
Here it will find the files in abcd directory .
2) How to find the files older than 7 days
using find command we can find the files greater than n days
find <path> -type f -mtime +7
mantis~$ find ./ -type f -mtime +7 CI_CD.odt qwerty.pem
3) How to To Replace String in A File
using sed command we can replace a string in a file
sed -i -e 's/old/new/g' hello.txt
sed -i -e 's/cat/dog/g' hello.txt
Here it will replace all the strings dog with cat
4) How to find the files greater than 1gb
find /path... -type f -size +1G
using find command we can find the files greater than 1gb. here it will all files greater than 1gb
5) How to List processes which are listening on a particular port
we can list the processes which are listening on a particular port using 'lsof' command
lsof -i :portnumber
lsof -i :8080
it will list all the process listening on port 8080
or
using below command we can display open sockets
lsof -n -P | grep LISTEN
lsof -n -P | grep LISTEN
or
netstat -tunlp
using netstat command also we can list the open ports
netstat -tunlp
6) difference b/w hard link and softlink in linux
hardlinks act as a shortcut to that file that is hard linked. inode of hardlink and file are same and hardlink cannot created for directories. Unlike a hard link, a symbolic link does not contain the data. when you delete a target file, symbolic links become unusable, whereas hard links preserve the contents of the file.
7) How to create a hardlink
using ln command we can create hardlink
ln <filename/path> <hardlinkname>
8) How to create a softlink
using ln -s command we can create softlink
ln -s <filename/path> <softlinkname>
9) what is symbolic link
Symbolic link known as soft link or symlink. It is shortcut to file or directory like in windows system. Soft Link contains the path of original file and not the content. softlink become inactive if you delete the original file. inode values of softlink and original files are different.
10) what is hard link
hard link also one type of pointer to a file. hard links and original file will have same i node values so the hard link represent the same original file location. hard links contains the file content. if you delete the original file still you will have the content in hard link. we can not create hard links for directories.
11) what is i node
Inode is a data structure that stores all the information about a file. Like size of the file, userid of the file, group id of the file, timestamps for file creation, modification..etc. Inode numbers uniquely exist for all the files on Linux.
12) How will you find the inode of a file
using ls -i command we can list all the files with their i node numbers.
172.17.12.1~:~$ ls -i 1019550 Applications 982931 Movies 1122935 hello 982879 Desktop 982874 Music 982865 Documents 982877 Pictures 982867 Downloads 982927 Public 982853 Library