Working with Files/Directories

Below are some simple examples of basic Linux commands for accessing and changing your files and directories. For all of these commands, you can run man command_name to see the manual page (system documentation) on the command, including an explanation of the available command line options.

  • Show the current “full path”, the directory you are working in with its parent and all levels of grandparents up to the root directory (/): 
    scc1$ pwd
/usr2/collab/adftest2
  • Create a file: 
    scc1$ touch myfile
    This command will create a blank file named myfile. You will also want to be able to use a text editor to create or modify an existing text file. A simple graphical editor to use is gedit, but more complex editors like emacs and vi are also available by default.
  • Create a directory: 
    scc1$ mkdir newdir
  • List items, including files and directories, in a directory: 
    scc1$ ls newdir
newdir

    There are many options to the ls command such as ls -l to list the files in a directory in “long” (verbose) format such as:

    scc1$ ls -l newdir
total 0
drwxr-xr-x 3 adftest2 adftest 512 Oct 28 16:03 newdir

    The letters on the left (“drwxr-xr-x”) indicate the “permissions” of this file/directory. The “d” indicates that it is a directory. The next 9 characters indicate that it is “readable”, “writable”, and “executable” by you and “readable” and “executable” by both the members of your project group and the world. The commands you can use to change these “permissions” are chmod and umask.

  • Move and/or rename a file: 
    scc1$ mv myfile newdir/newfilename

    This command will move the file myfile into the directory newdir and simultaneously rename it to newfilename.

  • Move to a different directory: 
    scc1$ cd newdir

    Move to the newly created newdir directory. You can also specify a “full path” (a path that starts with a /) such as cd /usr/local/bin. Typing just cd (or cd .) by itself will always take you to your home directory.

  • Move to the parent (next higher level) directory of the one you are in: 
    scc1$ cd ..

    This takes you up one level in the SCC directory structure.

  • Copy a file: 
    scc1$ cp newfilename filecopy

    This command will make a copy of newfilename and name it filecopy. You can copy entire directories by using the -r (recursive) option.

  • Delete a file: 
    scc1$ rm filecopy
rm: remove regular empty file `filecopy'? y

    By default you will be asked to confirm that you want to remove a file by typing y. You could avoid this by using the command line option -f but then you must be much more careful. Empty directories are removed using the command rmdir directory_name. Full directories can be removed by again using the -r (recursive) option to rm.

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Tar and Compressed Files🔗

There are four main archiving (combining multiple files into one archive file) and compression (reducing the size of a file) tools on Linux systems with associated tools to reverse the process. It is common to both archive a set of files and then compress the archive, such as a file named myarchive.tar.gz

Archive/ Compression Tool Unarchive /Uncompression Tool Archived/ Compressed Filename Extension Purpose
gzip gunzip .gz Compress a large single file
compress uncompress .Z Compress a large single file
zip unzip .zip Creating a single compressed file from a group of files
tar -c tar -x .tar Creating a single file from a group of files

Usage of the first two tools (gzip and compress) and their counterparts is straightforward:

scc1$ ls
myfile
scc1$ compress myfile # or replace with gzip
scc1$ ls
myfile.Z
scc1$ uncompress myfile.Z # or replace with gunzip of a .gz file
scc1$ ls
myfile

On Linux systems, tar is used much more commonly for archiving sets of files than zip. However, you may very well come across ZIP archives, often generated on Windows, which you will need to unzip:

scc1$ unzip example.zip
Archive:  example.zip
   creating: Packet1/
   creating: Packet2/
scc1$ ls
Packet1/     Packet2/     example.zip

Using Tar
Tar has many options. Shown below is an example of generating and then expanding a simple archive. Note that if you have a compressed tar file such as myarchive.tar.gz you will generally first want to uncompress it using the appropriate tool above and then untar it.

scc1$ ls mydir
file1  file2
scc1$ tar -cvf mydir.tar mydir/ # Generate the archive mydir.tar from the directory mydir and all of its contents.
mydir/
mydir/file1
mydir/file2
scc1$ rm -r mydir # Remove the original directory for now
scc1$ ls
mydir.tar
scc1$ tar -tvf mydir.tar # Look at what is in the archive file.
drwx------ aarondf/scv       0 2014-04-30 13:26 mydir/
-rw------- aarondf/scv       8 2014-04-30 13:25 mydir/file1
-rw------- aarondf/scv      10 2014-04-30 13:26 mydir/file2
scc1$ tar -xvf mydir.tar # Expand the archive file in my current directory.
mydir/
mydir/file1
mydir/file2
scc14 ls *
mydir:
file1  file2

mydir.tar