Command lines - Shell Shell system information uname -a print working directory pdw print application directory which _ create folder mkdir -p _ list all files (including hidden) ls -a view permission ls -l view permission (extended attributes) ls -l@ view permission as number (chmod) stat --format '%a' <file> permission (read only) chmod 400 _ permission (all user) chmod 755 _ permission (this user only) chmod 700 _ permission (executable) chmod +x _ permission (executable for this user only) chmod u+x _ view home directory echo $HOME view shell type echo $SHELL view value of PATH variable echo $PATH add a new path to PATH variable export PATH="$PATH:`pwd`/_" source .bash_profile from .zprofile if [ -r ~/.bash_profile ]; then source ~/.bash_profile fi source .bashrc from .bash_profile if [ -r ~/.bashrc ]; then source ~/.bashrc fi ddd path to .bashrc cd ~ vi .bashrc export PATH=$PATH:/_ :q! source ~/.bashrc echo $PATH recursively list folder content ls -R recursively list folder content with exclusion ls | grep -v 'name' recursively find all files with extension find . -name "*.___" -type f recursively delete all files with extension find . -name "*.___" -type f -delete recursively find all files with extension and copy to folder find . -name "*.___" -type f -exec cp {} ./foldername \; view available memory (RAM) free -h monitor system resources htop monitor disk space df -H