Terminal basics


  • ls: lists subdirectories or files in your current directory
  • pwd: gives your current directory
  • cat <file>: Outputs the contents of the file onto the terminal. Used to look at the contents of a file without opening it.
  • cd <target_directory>: Changes your current directory to the the specified target directory. The target directory must be in your current working folder/directory. You can check this by typing the ls command.
  • grep "<string>" <file> : This is the most basic usage of grep, for more flags/options, see here and here. Some usage flags include: -i : ignore case, -H : with file name (prints file name where each match is found), -L stops at first match.
  • touch <file>: can be used to create a file in the current working directory, or in the directory provided like this -> touch <path_to_file>.
  • sed : Extremely powerful tool, Sed, the ultimate stream editor. We can substitute words(like find and replace tool) using regex and so much more. Some examples would be:
sed -i 's/old/new/g' file

This would replace "old" with "new" for all occurrence's in file. For information on sed can be found here.

  • <command1>|<command2>: The pipe command transfers the output of a given command (Here output of command1 is transferred to command2). For example if I wanted to transfer
  • > and >>: The '>' operator overwrites the existing file, or creates the file if file mentioned cannot be found. The '>>' operator appends to the existing file, or creates the file if file does not exist. See script below. Usage of the operators would be :{command_with_output} > file . Here is an example of a simple shell script.
# This is script I wrote that will append the given data to the file logger.md
echo -n "Enter line to be appended: "
read userinput
echo "$userinput" >> ~/Documents/logger.md