Bash: echo $? - exit status of last command (0 no error) ' - Single quote removes meaning special meaning of special character. find /qwe -type f -iname *.js -exec cp --parents -t /tmp/ {} + -- find all js files and copy with parent directory ystemctl set-default graphical.target (ls -l /lib/systemd/system/runlevel*) -- set runlevel echo <password> | sudo -S for i in t@01 st@02 ba@sta03;do ssh -o RequestTTY=true $i "sudo -l";done -- allow tty present VIM: :r! sed -n '16,812 p' < input_file.txt -- copy line range from input_file :1,10d -- delete line from 1 to 10 :se nu -- show line numbers Apache: Redirection in Apache (By default, the Redirect directive establishes a 302, or temporary, redirect.): URL:https://www.digitalocean.com/community/tutorials/how-to-create-temporary-and-permanent-redirects-with-apache-and-nginx <VirtualHost *:80> ServerName www.domain1.com Redirect 301 /oldlocation http://www.domain2.com/newlocation </VirtualHo