DOS vs. Linux Commands To Remember

Command's Purpose	MS-DOS	Linux	Basic Linux Example
Copies files	copy	cp	cp thisfile.txt /home/thisdirectory
Moves files	move	mv	mv thisfile.txt /home/thisdirectory
Lists files	dir	ls	ls
Clears screen	cls	clear	clear
Closes prompt window	exit	exit	exit
Displays or sets date	date	date	date
Deletes files	del	rm	rm thisfile.txt
"Echoes" output on the screen	echo	echo	echo this message
Edits files with simple text editor	edit	pico	pico thisfile.txt
Compares the contents of files	fc	diff	diff file1 file2
Finds a string of text in a file	find	grep	grep this word or phrase thisfile.txt
Formats a diskette	format a: (if diskette is in A:)	mke2fs	/sbin/mke2fs /dev/fd0 (/dev/fd0 is the Linux equivalent of A:)
Displays command help	command /?	man	man command
Creates a directory	mkdir	mkdir	mkdir directory
View a file	more	less	less thisfile.txt
Renames a file	ren	mv	mv thisfile.txt thatfile.txt
Displays your location in the file system	chdir	pwd	pwd
Changes directories with a specified path (absolute path)	cd pathname	cd pathname	cd /directory/directory
Changes directories with a relative path	cd ..	cd ..	cd ..
Displays the time	time	date	date
Shows amount of RAM and use	mem	free	free

source : Redhat Docs