Linux Commands

Philosophy of using command line is that input and output files are files.

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Basic Commands:

Correct grammar of command is: verb adverb object
where adverb is the flag you add to a command e.g -hl in ls -hl

To view the flags for a command use man e.g man ls

• cd - go back to previous directory you were in
• ls list files in a directory
  • ls -hl more human readable version of ls -l
  • ls -t order by modification date, newest first
• cp copy a file
  • cp data1 data3 copies a data1 file to data3
• cp -r to copy a folder with files inside
• rm remove a file
• mv changes a file name
• cat output contents of the file
  • head output top part of the file
    • use -n flag to choose the number of lines e.g -5
  • tail print top part of the file
• less opens a pager to view a file
  • within the pager can use / to search in the file then press n to search for the next file.
• grep is used to search a file e.g grep "fish" king-lear.txt
  • to count the number of lines in a text file add -c tag grep -c "fish" king-lear.txt
  • to be case insensitive use -i
  • use regular expressions with grep for example wildcard *
  • search in all files and files in subdirectories with -r tag

  Shell scripts are just a text file where we can store linux commands

Useful

• Making google chrome the default application to open .pdf extensions, run in terminal:

xdg-mime default google-chrome.desktop application/pdf