Working With Files and Directories#

Names for Files and Directories#

Complicated names of files and directories can make your life very painful when working on the command line. Here we provide a few useful tips for the names of your files from now on.

  1. Don’t use whitespaces.

    White spaces can make a name more meaningful but since whitespace is used to break arguments on the command line is better to avoid them on name of files and directories. You can use - or _ instead of whitespace.

    Commands treat names starting with - as options.

  2. Stay with letters, numbers, . (period), - (dash) and _ (underscore).

  3. Don’t begin the name with -.

If you need to refer to names of files or directories that have whitespace or another non-alphanumeric character you should put quotes around the name.

Copying, Moving, and Deleting#

Copying#

Copy a file with cp:

$ cp oldfile newfile

To copy a file into a directory:

$ cp filename /path/to/directory

This will make a copy of filename with same name in directory.

Moving#

Move a file with mv:

$ mv oldfile newfile

The move command is also the command to rename a file.

$ mv filename directory

The above command will move filename into the existing directory.

Note

cp and mv can overwrite files which is irreversible. Using the -i flag with cp or mv will prompt you before overwriting an existing file.

Deleting#

Remove a file with rm:

$ rm filename

The opposite of mkdir is rmdir:

$ rmdir directory

rmdir only works for empty directories. To delete a directory and all it’s contents pass the -r or --recursive flag to rm:

$ rm -r directory

Deleting Is Forever#

Files deleted with rm cannot be recovered from a trash bin. Be very careful when deleting files especially with rm -r.

Wildcards#

File globbing, known better as wildcards, uses patterns to automatically expand a file name or path. The * character matches any (multiple) characters. A ? matches a single character.

Example:

$ ls
example1.txt    hello1.txt    hello2.txt    hello3.txt

$ ls *.txt
example1.txt    hello1.txt    hello2.txt    hello3.txt  hello4.csv

$ ls hello*
hello1.txt    hello2.txt    hello3.txt  hello4.csv

$ ls hello?.txt
hello1.txt    hello2.txt    hello3.txt

Viewing Contents of a File#

There are many different ways to view the contents of a file.

  • more and less will display the file in a buffer

    • contents will fill the size of your terminal, allowing you to scroll

$ less file

  • cat will print the contents of the file to the terminal

    • not recommended with large text files, use more or less instead

$ cat file

  • head will display the first 10 lines of the file

  • head -n X will display the first X lines of the file

$ head file

$ head -n 20 file

  • tail will display the last 10 lines of the file

  • tail -n X will display the last X lines of the file

$ tail file

$ tail -n 20 file

  • tail -f will display the last 10 lines and continue displaying lines as the file is updated

$ tail -f logfile