DOS Command: dir, dir/w
Linux Equivalent: ls, ls -l

DOS Command: chdir (Current directory)
Linux Equivalent: pwd

DOS Command: del (remove a file)
Linux Equivalent: rm

DOS Command: deltree (remove a directory and all files under it)
Linux Equivalent: rm -r

DOS Command: copy
Linux Equivalent: cp

DOS Command: xcopy (copy all files in a directory and under it)
Linux Equivalent: cp -R

DOS Command: rename, move
Linux Equivalent: mv

DOS Command: type (print contents of a file to the screen)
Linux Equivalent: cat

DOS Command: help, <command> /?
Linux Equivalent: man

DOS Command: cls (clear screen)
Linux Equivalent: clear

DOS Command: find (search for a word or words in a specified file)
Linux Equivalent: grep

DOS Command: fc (compare two files and find differences between them)
Linux Equivalent: diff

DOS Command: set (show environment variables)
Linux Equivalent: env

DOS Command: set variable (set environment variable)
Linux Equivalent: export

DOS Command: edit filename
Linux Equivalent: vi filename, pico filename, nano -w filename (varies based on editor of choice)

DOS Command: attrib +h filename (makes a file hidden)
Linux Equivalent: mv file .file

DOS Command: mem (displays available memory)
Linux Equivalent: free, top

DOS Command: scandisk
Linux Equivalent: fsck

DOS Command: defrag c:\
Linux Equivalent: debugfs

DOS Command: format
Linux Equivalent: mke2fs, mk32fs -j, mkreiserfs, mkswap, etc. (varies based on desired filesystem)

DOS Command: pkzip (creates archive of file)
Linux equivalent: tar, used often in conjunction with gzip for compression)

DOS Command: tracert
Linux Equivalent: traceroute

DOS Command: ipconfig (check IP address and network settings)
Linux Equivalent: ifconfig

DOS Command: nbtstat -a hostname (get DNS info for specified host)
Linux Equivalent: nslookup hostname

DOS Command: route print (display routing table)
Linux Equivalent: route -n

DOS Command: net send host/ip message send message to another computer
Linux Equivalent: smbclient -M Windows Host, talk (Linux hosts)