Speed your downloads, get to the bottom of the problem, and tweak your desktop with the right Terminal inputs.
Learn more here, here, here, here and here.
A quick reference list from ss64.com follows:
alias Create an alias • alloc List used and free memory apropos Search the whatis database for strings awk Find and Replace text within file(s) b basename Convert a full pathname to just a filename bash Bourne-Again SHell bg Send to background • bind Display readline key and function bindings • bless Set volume bootability and startup disk options. break Exit from a For, While, Until or Select loop • builtin Execute a shell builtin • bzip2 Compress or decompress files c cal Display a calendar calendar Reminder Service caller Return the context of a subroutine call • case Conditionally perform a command • cat Concatenate and print (display) the content of files cd Change Directory • chflags Change a file or folder's flags chgrp Change group ownership chmod Change access permissions chown Change file owner and group chroot Run a command with a different root directory cksum Print CRC checksum and byte counts clear Clear terminal screen cmp Compare two files comm Compare two sorted files line by line command Run a command (not a function) • complete Edit a command completion [word/pattern/list] • continue Resume the next iteration of a loop • cp Copy one or more files to another location cron Daemon to execute scheduled commands crontab Schedule a command to run at a later date/time csplit Split a file into context-determined pieces curl Transfer data from or to a server cut Divide a file into several parts d date Display or change the date & time dc Desk Calculator dd Data Dump - Convert and copy a file declare Declare variable & set attributes • defaults Set preferences, show hidden files df Display free disk space diff Display the differences between two files diff3 Show differences among three files dig DNS lookup dirname Convert a full pathname to just a path dirs Display list of remembered directories • diskutil Disk utilities - Format, Verify, Repair disown Unbind a job from the current login session • ditto Copy files and folders dot_clean Remove dot-underscore files drutil Interact with CD/DVD burners dscacheutil Query or flush the Directory Service/DNS cache dseditgroup Edit, create, manipulate, or delete groups dsenableroot Enable root access dsmemberutil View user and groups rights dscl Directory Service command line utility du Estimate file space usage e echo Display message on screen • ed A line-oriented text editor (edlin) enable Enable and disable builtin shell commands • env List or Set environment variables eval Evaluate several commands/arguments • exec Execute a command • exit Exit the shell • expand Convert tabs to spaces expect Programmed dialogue with interactive programs Also see AppleScript export Set an environment variable • expr Evaluate expressions f false Do nothing, unsuccessfully fc Fix command (history) fdisk Partition table manipulator for Darwin UFS/HFS/DOS fg Send job to foreground • file Determine file type find Search for files that meet a desired criteria fmt Reformat paragraph text fold Wrap text to fit a specified width for Loop command • fsck Filesystem consistency check and repair fsaclctl Filesystem enable/disable ACL support fs_usage Filesystem usage (process/pathname) ftp Internet file transfer program g GetFileInfo Get attributes of HFS+ files getopt Parse positional parameters getopts Parse positional parameters • goto Jump to label and continue execution grep Search file(s) for lines that match a given pattern groups Print group names a user is in gzip Compress or decompress files h halt Stop and restart the operating system hash Refresh the cached/remembered location of commands • head Display the first lines of a file hdiutil Manipulate iso disk images history Command History • hostname Print or set system name i iconv Convert the character set of a file id Print user and group names/id's if Conditionally perform a command • ifconfig Configure network interface parameters ipconfig View and control IP configuration state info Help info install Copy files and set attributes j jobs List active jobs • join Join lines on a common field k kextfind List kernel extensions kickstart Configure Apple Remote Desktop kill Stop a process from running l l List files in long format (ls -l) last Indicate last logins of users and ttys launchctl Load or unload daemons/agents ll List files in long format, showing invisible files (ls -la) less Display output one screen at a time let Evaluate expression • lipo Convert a universal binary ln Make links between files (hard links, symbolic links) local Set a local (function) variable • locate Find files logname Print current login name login log into the computer logout Exit a login shell (bye) • look Display lines beginning with a given string lpr Print files lprm Remove jobs from the print queue lpstat Printer status information ls List information about file(s) lsregister Reset the Launch Services database lsbom List a bill of materials file lsof List open files m man Help manual mdfind Spotlight search mdutil Manage Spotlight metadata store mkdir Create new folder(s) mkfifo Make FIFOs (named pipes) more Display output one screen at a time mount Mount a file system mv Move or rename files or directories n nano Simple text editor net Manage network resources netstat Show network status networksetup Network and System Preferences nice Set the priority of a command nohup Run a command immune to hangups ntfs.util NTFS file system utility o onintr Control the action of a shell interrupt open Open a file/folder/URL/Application opensnoop Snoop file opens as they occur osacompile Compile Applescript osascript Execute AppleScript p passwd Modify a user password paste Merge lines of files pbcopy Copy data to the clipboard pbpaste Paste data from the Clipboard ping Test a network connection pkgutil Query and manipulate installed packages plutil Property list utility pmset Power Management settings popd Restore the previous value of the current directory • pr Convert text files for printing printenv List environment variables printf Format and print data • ps Process status pushd Save and then change the current directory pwd Print Working Directory • q quota Display disk usage and limits r rcp Copy files between machines read Read one line from standard input • readonly Mark a variable or function as read-only • reboot Stop and restart the system return Exit a function • rev Reverse lines of a file rm Remove files rmdir Remove folder(s) rpm Remote Package Manager rsync Remote file copy - Sync file tree (also RsyncX) s say Convert text to audible speech screen Multiplex terminal, run remote shells via ssh screencapture Capture screen image to file or disk sdiff Merge two files interactively security Administer Keychains, keys, certificates and the Security framework sed Stream Editor select Generate a list of items • set Set a shell variable = value • setfile Set attributes of HFS+ files shift Shift positional parameters • shopt Set shell options • shutdown Shutdown or restart OS X sips Scriptable image processing system sleep Delay for a specified time softwareupdate System software update tool sort Sort text files source Execute commands from a file • split Split a file into fixed-size pieces stop Stop a job or process su Substitute user identity sudo Execute a command as another user sum Print a checksum for a file suspend Suspend execution of this shell • sw_vers Print Mac OS X operating system version system_profiler Report system configuration systemsetup Computer and display system settings t tail Output the last part of files tar Tape ARchiver tcpdump Dump traffic on a network tee Redirect output to multiple files test Condition evaluation • textutil Manipulate text files in various formats (Doc,html,rtf) time Measure Program Resource Use times Print shell & shell process times • top Display process information touch Change file timestamps tr Translate, squeeze, and/or delete characters trap Execute a command when the shell receives a signal • traceroute Trace Route to Host true Do nothing, successfully tty Print filename of terminal on stdin type Describe a command • u ufs.util Mount/unmount UFS file system ulimit limit the use of system-wide resources • umask Users file creation mask umount Unmount a device unalias Remove an alias • uname Print system information unexpand Convert spaces to tabs uniq Uniquify files units Convert units from one scale to another unset Remove variable or function names • until Loop command • uptime Show how long system has been running users Print login names of users currently logged in uuencode Encode a binary file uudecode Decode a file created by uuencode uuidgen Generate a Unique ID (UUID/GUID) uucp Unix to Unix copy v vi Text Editor w wait Wait for a process to complete • wc Print byte, word, and line counts whatis Search the whatis database for complete words where Report all known instances of a command which Locate a program file in the user's path while Loop command • who Print all usernames currently logged on whoami Print the current user id and name (`id -un') write Send a message to another user x xargs Execute utility - passing arguments yes Print a string until interrupted !! Run the last command again
