Unix Commands

Nov 5, 2022

• Software engineering
• Linux
• Shell
• Scripting

• Stanford’s Basic Unix Commands

To get the current user in a shell or script, run the below command

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whoami

or

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echo "$USER"

• Template command to remotely run a script and immediately exit, without caring about the result. This is useful for automation scripts that involve running multiple commands on remote servers.

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ssh -q $SSH_USER@$SERVER "nohup /appl/bin/start.sh start > /dev/null 2>&1 & "

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nslookup www.google.com

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curl ifconfig.me

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ifconfig -a

• du -sh -- *

lsof -p PID will list all the files that have been touched by the currently running process

• Search contents of every file for this matching text: find . -type f -exec egrep -lH search_for_me '{}' ';'

• Find every file named config.txt in your home directory: find ~ -name "config.txt"

• scp command cheat sheet

• Copy a file from a local to a remote system: scp file.txt ssh_user@hostname:/tmp

• List all certs in a keystore: keytool -list -keystore <PATH_TO_CACERTS> -storepass changeit -noprompt
• Add a cert to a keystore: keytool -import -trustcacerts -keystore <PATH_TO_CACERTS> -storepass changeit -noprompt -alias <ALIAS> -file <PATH_TO_NEW_CERT>
• Delete cert in a keystore by alias: keytool -delete -alias <ALIAS> -keystore <PATH_TO_CACERTS>

• Verify contents of a cert: openssl x509 -in <PATH_TO_CERT> -text
• View certs of a client: openssl s_client -showcerts -connect google.com:636

• chown -h USER:GROUP jre if you want to change the ownership of the symlink itself, not the destination directory

• Handy command for Mac to check what process is using a port

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sudo lsof -i :3306

• If you’re on Mac You can also look up and stop processes via the Activity Monitor GUI.
  • If you wanted to stop a java process, for example, you could go to the Disk section, and filter by java processes.