BASH Scripting Cheat Sheet

A cheat sheet in English by datamansam

3,096 views 684 downloads 28 May 2022 History

PRs

Lists and List Options

ls	List all values in present working directory
ls -R	List all files in sub-directories as well
ls -a	List hidden files as well

Moving and Renaming Files

mv file "new file path"	Moves the files to the new location
mv filename new_file_name	Renames the file to a new filename

Insert mode

i	insert at cursor
a	Write after cursor
A	Write at end of line
ESC	Terminate insert mode
u	Undo last change
U	undo change to entire last line

For loop

# For loop in Bash; Basic
for x in 1 2 3
do
    echo $x
done
1
2
3

# For loop in Bash; Range
{START..STOP..INCREMENT}
for x in {1..5..2}
do
    echo $x
done
Output:
1
2
5


# For loop; Three expression 
for ((x=2;x<=4;x+=2))
do
    echo $x
done

Output:
2
4

Home Directory

cd	Navigate to home directory
cd ..	Move one level up
cd /	Move to root directory

Process Management

ps	Display currently running processes
ps -ef	Display currently running processes on system

Search Files

grep pattern files	grep 'word' filename
grep -i	Case insensitive search
grep -R 'httpd'	Look for all files in the current directory and in all of its subdirectories
grep -c 'nixcraft' frontpage.md	Search and display the total number of times that the string ‘nixcraft’ appears in a file

Directory with a for loop

# Search for books in the book directory that contain air

for book in $(ls books/ | grep -i 'air')
do
    echo $book
done

AirportBook.txt
FairMarketBook.tx

Case Statements

case 'STRING' in
PATTERN1)
COMMAND1;;
PATTERN2)
COMMAND2;;
*)
DEFAULT COMMAND;;
esac

case $(cat $1) in
*sydney*)
mv $1 sydney/ ;;
*melbourne*|*brisbane*)
rm $1 ;;
*canberra*)
mv $1 "IMPORTANT_$1" ;;
*)
echo "No cities found" ;;
esac

Creating and viewing a file

Creates a new file	cat > filename
Displays the file content	cat filename

BASH variables

Set with an equal sign	greeting="Hello"
Access with a $	echo $greeting

Control Flow

Direct Output of Second command to first	1st_command $ 2nd Command
Runs the 2nd command only if the 1st command runs successfully.	1stcommand && 2nd Command
Runs the 2nd command only if the 2nd command does not run successfully.	A \|\| B # Run B if and only if A failed

While Statement

Set a condition which is tested at each iteration:

x=1
while [ $x -le 3 ];
do
    echo $x
     ((x+=1))
done

if, then, else statement

if then else:
x="Queen"
if [ CONDITION ];
if [ $x == "King" ];
then # SOME CODE
then echo "$x is a King!"
else # SOME OTHER CODE
else echo "$x is not a King!"
fi
fi

Navigating With Cursor

Alt + b	move backward one word
Alt + f	move forward one word
Alt + u	make entire word after cursor uppercase
Alt + c	make first letter after cursor uppercase
Alt + d	delete word after cursor
^a	beginning of line
^e	end of line

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