Section B.1 Bash Shell Cheat Sheet
Getting help with shell commands.
man <command-name>
-
Use the built-in manual.
- e.g.
man cd
retrieves the manual for the change directory command.
<command-name> --help
-
Request the help page (when it exists) for the specified command. Note that not every command supports
--help
.- e.g.
cd --help
retrieves help for the change directory command.
File and Directory Commands.
pwd
-
Print working directory displays the path of the current working directory.
- e.g.
pwd
prints the path of the current working directory.
whoami
-
The whoami prints the userid of the current user.
- e.g.
whoami
prints the userid.
ls
-
List displays basic information about files and directories.
- e.g.
ls
lists directories and files in the current directory. - e.g.
ls -l
lists directories and files in the current directory using a long listing. - e.g.
ls ~
lists directories and files in the user’s home directory.
touch <file-name>
-
The touch command is commonly used for file creation. Its intended primary function is to update its timestamp, by "touching" it. See
man touch
for more information on the intended use.- e.g.
touch newfile.txt
creates an empty file named newfile.txt.
cd <directory-name>
mv <old-name> <new-name>
rm <file-name>
mkdir <directory-name>
rmdir <directory-name>
The Basics: Reading, Writing, Counting, etc.
echo <text>
- The echo command displays a line of text and/or requests the value of a variable from the shell and displays its value. Often used with output redirection.
- e.g.
echo 'Hello World!'
print the text ’Hello World!’ on the standard output. - e.g.
echo $USER
prints the value of the USER environment variable on the standard output.
cat <file-name>
- The concatenate prints file contents on the standard output after concatenation. Note that with a single file, it just prints that file. It is often used with output redirection.
- e.g.
cat file.txt
prints the contents of file.txt on the standard output. - e.g.
cat file1.txt file2.txt
prints the contents of the concatenation of file1.txt and file2.txt on the standard output.
read <variable-name>
wc <file-name>
history
- The history command displays a list of previously executed shell commands, allowing users to review their command history.
-
e.g.
history
could display:1 git init 2 git add main.c 3 git commit -m "Initial commit" 4 git remote add origin https://github.com/username/repo.git 5 git push -u origin master 6 history
-
Input and Output Redirection.
- Input redirection using
<
- Output redirection using
>
or>>
- Output redirection allows the user to redirect the output from the standard output to a file using
>
for overwriting or>>
for appending.- e.g.
echo 'I love open source!' > file.txt
writes the line ’I love open source!’ into the file file.txt replacing the current contents or making a new file if it doesn’t already exist.
- Piping
|
File Permissions.
chown <newuser:newgroup> <file-name>
chmod <change><which> <file-name>
-
The
chmod
command is used to change permissions. The following symbols are the most commonly used:+
change by adding permission-
change by removing permissionr
which permission: readw
which permission: writex
which permission: execute- e.g.
chmod +x helloworld.sh
adds execute permission for all users to the helloworld.sh file.
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