Navigating Files and Directories
OverviewTeaching: 15 min
Exercises: 10 minQuestions
How can I move around on my computer?
How can I see what files and directories I have?
How can I specify the location of a file or directory on my computer?Objectives
Explain the similarities and differences between a file and a directory.
Translate an absolute path into a relative path and vice versa.
Construct absolute and relative paths that identify specific files and directories.
The part of the operating system responsible for managing files and directories is called the file system. It organizes our data into files, which hold information, and directories (sometimes called “folders”), which hold files or other directories.
Several commands are frequently used to create, inspect, rename, and delete files and directories. To start exploring them, we’ll go to our open shell window:
First let’s find out where we are by running a command called
(which stands for “print working directory”). Directories are like places - at any time
while we are using the shell we are in exactly one place, called
our current working directory. Commands mostly read and write files in the
current working directory, i.e. “here”, so knowing where you are before running
a command is important.
pwd shows you where you are:
the computer’s response is
which is Nelle’s home directory:
Home Directory Variation
The home directory path will look different on different operating systems. On Linux it may look like
/home/nelle, and on Windows it will be similar to
C:\Documents and Settings\nelleor
C:\Users\nelle. (Note that it may look slightly different for different versions of Windows.) In future examples, we’ve used Mac output as the default - Linux and Windows output may differ slightly, but should be generally similar.
To understand what a “home directory” is, let’s have a look at how the file system as a whole is organized. For the sake of this example, we’ll be illustrating the filesystem on our scientist Nelle’s computer. After this illustration, you’ll be learning commands to explore your own filesystem, which will be constructed in a similar way, but not be exactly identical.
On Nelle’s computer, the filesystem looks like this:
At the top is the root directory
that holds everything else.
We refer to it using a slash character
/ on its own;
this is the leading slash in
Inside that directory are several other directories:
bin (which is where some built-in programs are stored),
data (for miscellaneous data files),
Users (where users’ personal directories are located),
tmp (for temporary files that don’t need to be stored long-term),
and so on.
We know that our current working directory
/Users/nelle is stored inside
/Users is the first part of its name.
we know that
/Users is stored inside the root directory
because its name begins with
Notice that there are two meanings for the
/character. When it appears at the front of a file or directory name, it refers to the root directory. When it appears inside a name, it’s a separator.
Now let’s learn the command that will let us see the contents of our
own filesystem. We can see what’s in our home directory by running
which stands for “list”:
Applications Documents Library Music Public Desktop Downloads Movies Pictures
(Again, your results may be slightly different depending on your operating system and how you have customized your filesystem.)
ls prints the names of the files and directories in the current directory.
We can make its output more comprehensible by using the flag
(also known as a switch or an option) ,
ls to add a marker to file and directory names to indicate what
they are. A trailing
/ indicates that this is a directory. Depending on your
settings, it might also use colors to indicate whether each entry is a file or
You might recall that we used
ls -F in an earlier example.
$ ls -F
Applications/ Documents/ Library/ Music/ Public/ Desktop/ Downloads/ Movies/ Pictures/
ls has lots of other flags. There are two common ways to find out how
to use a command and what flags it accepts:
- We can pass a
--helpflag to the command:
$ ls --help
- We can read its manual with
$ man ls
If you use a Mac, or Git for Windows, you might find that only one of these works
man on Mac and
--help in Windows).
There is a third way: Search the Internet with your web browser or use TLDR pages website.
Many shell commands, and programs that people have written that can be
run from within bash, support a
--help flag to display more
information on how to use the command or program.
$ ls --help
Usage: ls [OPTION]... [FILE]... List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor --sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, --all do not ignore entries starting with . -A, --almost-all do not list implied . and .. --author with -l, print the author of each file -b, --escape print C-style escapes for nongraphic characters --block-size=SIZE scale sizes by SIZE before printing them; e.g., '--block-size=M' prints sizes in units of 1,048,576 bytes; see SIZE format below -B, --ignore-backups do not list implied entries ending with ~ -c with -lt: sort by, and show, ctime (time of last modification of file status information); with -l: show ctime and sort by name; otherwise: sort by ctime, newest first -C list entries by columns --color[=WHEN] colorize the output; WHEN can be 'always' (default if omitted), 'auto', or 'never'; more info below -d, --directory list directories themselves, not their contents -D, --dired generate output designed for Emacs' dired mode -f do not sort, enable -aU, disable -ls --color -F, --classify append indicator (one of */=>@|) to entries --file-type likewise, except do not append '*' --format=WORD across -x, commas -m, horizontal -x, long -l, single-column -1, verbose -l, vertical -C --full-time like -l --time-style=full-iso -g like -l, but do not list owner --group-directories-first group directories before files; can be augmented with a --sort option, but any use of --sort=none (-U) disables grouping -G, --no-group in a long listing, don't print group names -h, --human-readable with -l and/or -s, print human readable sizes (e.g., 1K 234M 2G) --si likewise, but use powers of 1000 not 1024 -H, --dereference-command-line follow symbolic links listed on the command line --dereference-command-line-symlink-to-dir follow each command line symbolic link that points to a directory --hide=PATTERN do not list implied entries matching shell PATTERN (overridden by -a or -A) --indicator-style=WORD append indicator with style WORD to entry names: none (default), slash (-p), file-type (--file-type), classify (-F) -i, --inode print the index number of each file -I, --ignore=PATTERN do not list implied entries matching shell PATTERN -k, --kibibytes default to 1024-byte blocks for disk usage -l use a long listing format -L, --dereference when showing file information for a symbolic link, show information for the file the link references rather than for the link itself -m fill width with a comma separated list of entries -n, --numeric-uid-gid like -l, but list numeric user and group IDs -N, --literal print raw entry names (don't treat e.g. control characters specially) -o like -l, but do not list group information -p, --indicator-style=slash append / indicator to directories -q, --hide-control-chars print ? instead of nongraphic characters --show-control-chars show nongraphic characters as-is (the default, unless program is 'ls' and output is a terminal) -Q, --quote-name enclose entry names in double quotes --quoting-style=WORD use quoting style WORD for entry names: literal, locale, shell, shell-always, shell-escape, shell-escape-always, c, escape -r, --reverse reverse order while sorting -R, --recursive list subdirectories recursively -s, --size print the allocated size of each file, in blocks -S sort by file size, largest first --sort=WORD sort by WORD instead of name: none (-U), size (-S), time (-t), version (-v), extension (-X) --time=WORD with -l, show time as WORD instead of default modification time: atime or access or use (-u); ctime or status (-c); also use specified time as sort key if --sort=time (newest first) --time-style=STYLE with -l, show times using style STYLE: full-iso, long-iso, iso, locale, or +FORMAT; FORMAT is interpreted like in 'date'; if FORMAT is FORMAT1<newline>FORMAT2, then FORMAT1 applies to non-recent files and FORMAT2 to recent files; if STYLE is prefixed with 'posix-', STYLE takes effect only outside the POSIX locale -t sort by modification time, newest first -T, --tabsize=COLS assume tab stops at each COLS instead of 8 -u with -lt: sort by, and show, access time; with -l: show access time and sort by name; otherwise: sort by access time, newest first -U do not sort; list entries in directory order -v natural sort of (version) numbers within text -w, --width=COLS set output width to COLS. 0 means no limit -x list entries by lines instead of by columns -X sort alphabetically by entry extension -Z, --context print any security context of each file -1 list one file per line. Avoid '\n' with -q or -b --help display this help and exit --version output version information and exit The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000). Using color to distinguish file types is disabled both by default and with --color=never. With --color=auto, ls emits color codes only when standard output is connected to a terminal. The LS_COLORS environment variable can change the settings. Use the dircolors command to set it. Exit status: 0 if OK, 1 if minor problems (e.g., cannot access subdirectory), 2 if serious trouble (e.g., cannot access command-line argument). GNU coreutils online help: <http://www.gnu.org/software/coreutils/> Full documentation at: <http://www.gnu.org/software/coreutils/ls> or available locally via: info '(coreutils) ls invocation'
The other way to learn about
ls is to type
$ man ls
This change your terminal from a shell prompt to a page with a description of the
ls command and its options and, in some cases, some examples of how to use it.
To navigate through the
you may use the up and down arrow keys to move line-by-line,
or try the “b” and spacebar keys to skip up and down by a full page.
To search for a character or word in the
use “/” followed by the character or word you are searching for.
To quit the
man pages, press
What does the command
lsdo when used with the
Some of its output is about properties that we do not cover in this lesson (such as file permissions and ownership), but the rest should be useful nevertheless.
lsuse a long listing format, showing not only the file/directory names but also additional information such as the file size and the time of its last modification. The
-hflag makes the file size “human readable”, i.e. display something like
Listing Recursively and By Time
ls -Rlists the contents of directories recursively, i.e., lists their sub-directories, sub-sub-directories, and so on at each level. The command
ls -tlists things by time of last change, with most recently changed files or directories first. In what order does
ls -R -tdisplay things? Hint:
ls -luses a long listing format to view timestamps.
The files or directories in each directory are sorted by time of last change.
We can see that our home directory contains mostly sub-directories. Any names in your output that don’t have trailing slashes, are plain old files. Also note that there is a space between
-F: Without it, the shell thinks we’re trying to run a command called
ls-F, which doesn’t exist.
We can also use
ls to see the contents of a different directory. Let’s take a
look at our
data-shell directory by running
ls -F data-shell,
ls with the
-F flag and the argument
we want a listing of something other than our current working directory:
$ ls -F data-shell
Your output should be a list of all the files and sub-directories in your
creatures/ molecules/ notes.txt solar.pdf data/ north-pacific-gyre/ pizza.cfg writing/
As you may now see, using a bash shell is strongly dependent on the idea that your files are organized in a hierarchical file system. Organizing things hierarchically in this way helps us keep track of our work: it’s possible to put hundreds of files in our home directory, just as it’s possible to pile hundreds of printed papers on our desk, but it’s a self-defeating strategy.
Also we can change our location to a different directory.
The command to change locations is
cd followed by a
directory name to change our working directory.
cd stands for “change directory”,
which is a bit misleading:
the command doesn’t change the directory,
it changes the shell’s idea of what directory we are in.
Let’s say we want to move to the
data directory we saw above. We can
use the following command to get there:
$ cd data
This will move us from our
data-shell directory into the
cd doesn’t print anything,
but if we run
pwd after it, we can see that we are now
If we run
ls without arguments now,
it lists the contents of
because that’s where we now are:
$ ls -F
amino-acids.txt elements/ pdb/ salmon.txt animals.txt morse.txt planets.txt sunspot.txt
We now know how to go down the directory tree, but how do we go up? We might try the following:
$ cd data-shell
-bash: cd: data-shell: No such file or directory
But we get an error! Why is this?
With our methods so far,
cd can only see sub-directories inside your current directory. There are
different ways to see directories above your current location; we’ll start
with the simplest.
There is a shortcut in the shell to move up one directory level that looks like this:
$ cd ..
.. is a special directory name meaning
“the directory containing this one”,
or more succinctly,
the parent of the current directory.
if we run
pwd after running
cd .., we’re back in
The special directory
.. doesn’t usually show up when we run
ls. If we want
to display it, we can give
$ ls -F -a
./ .bash_profile data/ north-pacific-gyre/ pizza.cfg thesis/ ../ creatures/ molecules/ notes.txt solar.pdf writing/
-a stands for “show all”;
ls to show us file and directory names that begin with
As you can see,
it also displays another special directory that’s just called
which means “the current working directory”.
It may seem redundant to have a name for it,
but we’ll see some uses for it soon.
Note that in most command line tools, multiple flags can be combined
with a single
- and no spaces between the flags:
ls -F -a is
Other Hidden Files
In addition to the hidden directories
., you may also see a file called
.bash_profile. This file usually contains shell configuration settings. You may also see other files and directories beginning with
.. These are usually files and directories that are used to configure different programs on your computer. The prefix
.is used to prevent these configuration files from cluttering the terminal when a standard
lscommand is used.
cd are the basic commands for navigating the filesystem on your computer.
Let’s explore some variations on those commands. What happens if you type
cd on its own, without giving
How can you check what happened?
pwd gives us the answer!
It turns out that
cd without an argument will return you to your home directory,
which is great if you’ve gotten lost in your own filesystem.
Let’s try returning to the
data directory from before. We can actually string together the list of directories
to move to
data in one step:
$ cd data-shell/data
Check that we’ve moved to the right place by running
If we want to move up one level from the data directory, we could use
cd ... But
there is another way to move to any directory, regardless of your
So far, when specifying directory names, or even a directory path (as above),
we have been using relative paths. When you use a relative path with a command
cd, it tries to find that location from where we are,
rather than from the root of the file system.
It is possible to specify the absolute path to a directory by
including its entire path from the root directory, which is indicated by a
leading slash. The leading
/ tells the computer to follow the path from
the root of the file system, so it always refers to exactly one directory,
no matter where we are when we run the command.
This allows us to move to our
data-shell directory from anywhere on
the filesystem (including from inside
data). To find the absolute path
we’re looking for, we can use
pwd and then extract the piece we need
to move to
$ cd /home/username/data-shell/data
ls -F to ensure that we’re in the directory we expect.
Two More Shortcuts
The shell interprets the character
~(tilde) at the start of a path to mean “the current user’s home directory”. For example,
cd ~/data-shell/datais equivalent to
/home/username/data-shell/data. This only works if it is the first character in the path:
here/there/~/elsewheredoes not produce
Another shortcut is the
-into the previous directory I was in, which is faster than having to remember, then type, the full path. This is a very efficient way of moving back and forth between directories. The difference between
cd -is that the former brings you up, while the latter brings you back. You can think of it as the Last Channel button on a TV remote.
Absolute vs Relative Paths
/Users/amanda/data/, which of the following commands could Amanda use to navigate to her home directory, which is
.stands for the current directory.
/stands for the root directory.
- No: Amanda’s home directory is
- No: this goes up two levels, i.e. ends in
~stands for the user’s home directory, in this case
- No: this would navigate into a directory
homein the current directory if it exists.
- Yes: unnecessarily complicated, but correct.
- Yes: shortcut to go back to the user’s home directory.
- Yes: goes up one level.
The file system is responsible for managing information on the disk.
Information is stored in files, which are stored in directories (folders).
Directories can also store other directories, which forms a directory tree.
cd pathchanges the current working directory.
ls pathprints a listing of a specific file or directory;
lson its own lists the current working directory.
pwdprints the user’s current working directory.
/on its own is the root directory of the whole file system.
A relative path specifies a location starting from the current location.
An absolute path specifies a location from the root of the file system.
Directory names in a path are separated with
/on Unix, but
..means ‘the directory above the current one’;
.on its own means ‘the current directory’.