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Examples of Bash Shell Features.md

Module 2 Cheat Sheet - Introduction to Linux Commands

Getting information

Return your user name:
whoami
Return your user and group id:
id
Return operating system name, username, and other info:
uname -a
Display reference manual for a command:
man top
List available man pages, including a brief description for each command:
man -k .
Get help on a command:
curl --help
Return the current date and time:
date
List files and directories by date, newest to last:
ls -lrt
Find files in directory tree that end in .sh:
find -name \'\*.sh\'
Return path to present working directory:
pwd
Make a new directory:
mkdir new_folder
Change the current directory:

> Up one level:

cd ../

> To home:

cd ~` or `cd

> To some other directory: cd path_to_directory

Remove directory verbosely:
rmdir temp_directory -v

Monitoring system performance and status

List selection of/all running processes and their PIDs:
ps

ps -e
Display resource usage:
top
List mounted file systems and usage:
df

Creating, copying, moving, and deleting files:

Create an empty file or update existing file's timestamp:
touch a_new_file.txt
Copy a file:
cp file.txt new_path/new_name.txt
Change file name or path:
mv this_file.txt that_path/that_file.txt
Remove a file verbosely:
rm this_old_file.txt -v

Working with file permissions

Change/modify file permissions to 'execute' for all users:
chmod  +x  my_script.sh
Change/modify file permissions to 'execute' only for you, the current user:
chmod u+x my_file.txt
Remove 'read' permissions from group and other users:
chmod go-r

Displaying file and string contents

Display file contents:
cat my_shell_script.sh
Display file contents page-by-page:
more ReadMe.txt
Display first 10 lines of file:
head -10 data_table.csv
Display last 10 lines of file:
tail -10 data_table.csv
Display string or variable value:
echo "I am not a robot"  
echo "I am $USERNAME"

Basic text wrangling

Sorting lines and dropping duplicates:

Sort and display lines of file alphanumerically:
sort text_file.txt

> ##### In reverse order:

sort -r text_file.txt
Drop consecutive duplicated lines and display result:
uniq list_with_duplicated_lines.txt

Displaying basic stats:

Display the count of lines, words, or characters in a file:

> Lines:

wc  -l table_of_data.csv

> Words:

wc  -w my_essay.txt

> Characters:

wc  -m some_document.txt

Extracting lines of text containing a pattern:

Some frequently used options for grep:

Option Description
-n Print line numbers along with matching lines
-c Get the count of matching lines
-i Ignore the case of the text while matching
-v Print all lines which do not contain the pattern
-w Match only if the pattern matches whole words
Extract lines containing the word "hello", case insensitive and whole words only:
grep  -iw hello  a_bunch_of_hellos.txt
Extract lines containing the pattern "hello" from all files in the current directory ending in .txt:
grep  -l hello  *.txt

Merge two or more files line-by-line, aligned as columns:

Suppose you have three files containing the first and last names of your customers, plus their phone numbers.

Use paste to align file contents into a Tab-delimited table, one row for each customer:
paste first_name.txt last_name.text phone_number.txt
Use a comma as a delimiter instead of the default Tab delimiter:
paste -d "," first_name.txt last_name.text phone_number.txt

Use the cut command to extract a column from a table-like file:

Suppose you have a text file whos rows consist of first and last names of customers, delimited by a comma.

Extract first names, line-by-line:
cut -d "," -f 1 names.csv
Extract the second to fifth characters (bytes) from each line of a file:
cut -b 2-5 my_text_file.txt
Extract the characters (bytes) from each line of a file, starting from the 10th byte to the end of the line:
cut -b 10- my_text_file.txt

Compression and archiving

Archive a set of files:
tar -cvf my_archive.tar.gz file1 file2 file3
Compress a set of files:
zip my_zipped_files.zip file1 file2   
zip my_zipped_folders.zip directory1 directory2
Extract files from a compressed zip archive:
unzip my_zipped_file.zip 
unzip my_zipped_file.zip -d extract_to_this_direcory

Working with networking commands

hostname
Send packets to URL and print response:
ping  www.google.com
Display or configure system network interfaces:
ifconfig   
ip
Display contents of file at a URL:
curl  <url>
Download file from a URL:
wget  <url>

Authors

Jeff Grossman
Sam Propupchuk

My thanks to Skill Network ( for this page )