- echo
- ;
- pwd
- ls
- cd
- '.' directory, '..' directory, '~' directory
- '*', '?' for pattern matching
- '' single quotes
- mv
- mkdir
- curl
- curl (-o [file name]) -L [URL]
- cat
- less
- rm
- rm -i
- rmdir
- grep
- grep [string] [file_name]
- Reads the file and print all the lines that have the string.
- grep [stirng] [file_name] | less
- Displays the output not on the command screen, but on the another screen.
- The pipeline '|' means that the result of the left operand feeds the right operand.
- grep -c [string] [file_name]
- Returns the number of the strings in the file.
- grep [string] [file_name] | wc -l
- Returns the number of the strings in the file.
- curl -L https://tinyurl.com/zeyq9vc | grep fish
- Displays all the lines that contains 'fish'
- curl -L https://tinyurl.com/zeyq9vc | grep fish | wc -l
- Counts the number of 'fish' in the page.
- curl -L https://tinyurl.com/zeyq9vc | grep -c fish
- Counts the number of 'fish' in the page
- grep [string] [file_name]
- variables
- There are 3 types of variables used in the shell: local variables, environment variables, and shell variables.
- numbers='This is a message.'
- Variable assignment
- 'numbers' is a local variable.
- A local variable is a variable that is present within the current instance of the shell.
- echo $numbers
- Variable
- unset numbers
- Deletes the variable 'numbers'
- echo $LINES x $COLUMNS
- $LINES and $COLUMNS are called shell varaibles.
- A shell variable is a special variable that is set by the shell and is required by the shell in order to function correctly.
- echo $PATH
- $PATH is called an environment variable.
- An environment variable is available to any child process of the shell.
- If you try to run a program by entering its name, the shell finds the name in the working directory and the directories stored in PATH variable.
- The directories in PATH variable are separated by colons ':'.
- $PATH is searched from beginning to end, with the first matching executable being run.
- Executables in the current directory '.' are only executed if '.' is in $PATH
- PATH=$PATH:(new_directory)
- Add a new directory to PATH.
- PATH is set to be default after exiting the shell.
- help(command)
- screen
- screen -list
- See the list of screen processes.
- screen -S screen_name
- Start a screen process.
- kill pid_screen_name
- You can find the pid of the screen from 'screen -list' command.
- Ctrl + A + D
- Return to the parent screen
- There exists the only one parent screen. The rest of screens are child screens.
- screen -list
- A shell script is a file that contains shell commands.
- Writing shell scripts is called shelling programming.
- Make *.sh that contains the set of commands.
- Type ./*.sh. Then the commands in the file are executed in order.
- The shell in every terminal you open will run the commands in the file called '.bash_profile'(Mac, Windows) or '.bashrc'(Linux).
- Git Bash in Windows runs '.bash_profile' right after the shell has run.
- I found '.bash_profile' in the directory '/c/Users/{user_name}', which is the home directory of Windows.
- '.bash_profile' and '.bashrc' are hidden. To see hidden files, you should type ls -l -a, with -a option.
- In the Git Bash in Window, '.bash_profile' is written as follows by default.
if [ -f ~/.bashrc ]; then . ~/.bashrc; fi - This command runs the file '.bashrc'. Then, by editing '.bashrc' we can set the customized environment.
- You can design your prompt as you want. You just put into PS1 how to change the prompt.
$ PS1='$ ' - You can design your prompt in the site http://bashrcgenerator.com/.
- By putting the statement of setting PS1 in '.bashrc', you can use your design as the default setting.
- Using alias command, you can make a long command shorter.
$ alias ll='ls -la' - Remind ll will be replaced with 'ls -la'.
- So, you can add arguments of 'ls', for example:
$ ll directory - It is also possible to make alias as the default setting by putting the commands in '.bashrc'.
- You can see the list of alias by typing alias.
$ alias alias ll='ls -la'