Bash Commands

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PATH

echo $PATH to display the variables.

And use PATH DEFAULT=${PATH}:/path/to/file to add a new one.

pwd

shows the current dictionary.

find

find a file with given name:

find . -name file_name

cat

cat could read the file content and output as a standard output stream.

alias

Create a shortcut of a command, for example:

alias lll = ls -a

more, less, most

less = more + backward navigation

most = more + less + some other features

name more less most
forward navigation support support s
backward navigation limited s s
other features no some all of more and less

which

which ls display the location of executables.

| Pipeline

Receive the input stream and output as the input of another command.

history | grep ls

> Direction

Receive the input stream and overwrite to the file.

"aaa" > a.py

chmod

chmod 777 main.py add permission for the file to be executable.

the second parameter is person add/remove permission.

  • User
    • u: user
    • g: group
    • o: other
  • +/-
  • Permission
    • r: read
    • w: write
    • e: execute

whoami

existential crisis, to show the user name.

Run executable file in terminal

PATH

Type in ./clean instead of clean. Or, if you don’t want to type the ./ prefix every time, add the present working directory (the dot) to your PATH environment variable (e.g. in your ~/.bash_profile or its equivalent in another shell).