DevOps session 6: Linux commands for DevOps team

 

File commands:

ls : Display the folders present in the current working directory.

ls -al : formatted listing with hidden files

mkdir – create a directory with provided name.

cd devops– change directory to devops

pwd – show current directory

touch file – create or update file

cat > file – places standard input into file/Create a new file and you can provide some text from console. Then to exit the file editting, click on CTRL+D.

cat  file –Display the file content in the console.

cp file1 file2 – copy file1 to file2

cp -r dir1 dir2 – copy dir1 to dir2; create dir2 if it doesn’t exist

mv file1 file2 – rename or move file1 to file2 if file2 is an existing directory, moves file1 into directory file2

rm file – delete file

rm -r dir – delete directory dir

Screen shots will be attached soon...

Process Management

• ps – display your currently active processes
• top – display all running processes
• kill pid – kill process id pid
• killall proc – kill all processes named proc *
• bg – lists stopped or background jobs; resume a stopped job in the background
• fg – brings the most recent job to foreground
• fg n – brings job n to the foreground

File Permissions

• chmod octal file – change the permissions of file to octal, which can be found separately for user, group, and world by adding.

             4 – read (r)   2 – write (w)    1 – execute (x)
             Examples:
             chmod 777– read, write, execute for all
             chmod 755 – rwx for owner, rx for group and world For more options, see man chmod.

SSH

• ssh user@host – connect to host as user
• ssh -p port user@host – connect to host on port port as user
• ssh-copy-id user@host – add your key to host for user to enable a keyed or passwordless login

Searching

• grep pattern files – search for pattern in files
• grep -r pattern dir – search recursively for pattern in dir
• command | grep pattern – search for pattern in the output of command
• locate file – find all instances of file

System Info

• date – show the current date and time
• cal – show this month’s calendar
• uptime – show current uptime
• w – display who is online
• whoami – who you are logged in as
• finger user – display information about user
• uname -a – show kernel information
• cat /proc/cpuinfo – cpu information
• cat /proc/meminfo – memory information
• man command – show the manual for command
• df – show disk usage
• du – show directory space usage
• free – show memory and swap usage
• whereis app – show possible locations of app
• which app – show which app will be run by default

Compression

• tar cf file.tar files – create a tar named file.tar containing files
• tar xf file.tar – extract the files from file.tar
• tar czf file.tar.gz files – create a tar with Gzip compression
• tar xzf file.tar.gz – extract a tar using Gzip
• tar cjf file.tar.bz2 – create a tar with Bzip2 compression
• tar xjf file.tar.bz2 – extract a tar using Bzip2
• gzip file – compresses file and renames it to file.gz
• gzip -d file.gz – decompresses file.gz back to file

Network

• ping host – ping host and output results
• whois domain – get whois information for domain
• dig domain – get DNS information for domain
• dig -x host – reverse lookup host
• wget file – download file
• wget -c file – continue a stopped download