(addgroup) Adding group to a system.
(adduser) Adding user to a system.
(alias) Create an Alias.
(apropos) Search Help manual pages.
(apt-get) Package installer (For Debian).
(aptitude) Package installer (For Debian).
(aspell) Spell check.
(awk) Find and replace text,database sort/validate/index.
(basename) Strip directory and suffix from filenames.
(bash) GNU Bourne-Again SHell.
(bc) Arbitrary precision calculator language.
(bg) Send to background.
(break) Exit from a loop.
(bunzip2) Deompress named files.
(bzip2) Compress named files.
(cal) Displays calender.
(case) Conditionally performs a command.
(cat) Displays the content of a file.
(cd) Change Directory.
(cfdisk) Partition table manupulator.
(chgroup) Change group owner.
(chkconfig) Systen servise at Runlevel.
(chmod) Change access permission.
(chown) Change file and group owner.
(chroot) Run a command with different root directory.
(cksum) prints CRC checksum and bytecounts.
(clear) Clears terminal screen.
(cmp) Compares two files.
(comm) Compares two sorted files line by line.
(command) Runs a command thus ignoring shell functions.
(continue) Resumes 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 later anytime.
(csplit) Splits a file into context-determined pieces
(cut) Divides a file into several parts.
(date) Display/change date & time.
(dc) Desk Calculator.
(dd) Converts and copies a file, writes disk headers, boot records
(ddrescue) Data recovery tool.
(declare) Declares variable and give them attributes.
(df) Displays free disk space.
(diff) Displays the differences between two files.
(diff3) Shows differences among three files.
(dig) DNS lookup.
(dir) Briefly list directory contents.
(dircolors) Color setup - ls.
(dirname) Convert a full pathname to just a path.
(dirs) Displays list of remembered directories.
(dmesg) Prints kernel & driver messages.
(du) Estimates file space usage.
(echo) Displays message on screen.
(egrep) Search files for lines that match an external expression.
(eject) Ejects removable media.
(enable) Enables and disables built-in shell commands.
(env) Environment variables.
(ethtool) Ethernet card settings.
(eval) Evaluates several commands/arguements.
(exec) Executes a command.
(exit) Exit the shell.
(expand) Convert tabs into spaces.
(expect) Automate arbitrary applications accessed over a terminal.
(export) Set an environment variable.
(expr) Evaluates expressions.
(false) Doing nothing unsuccessfully.
(fdformat) Low level formatting of floppy disk.
(fdisk) Partition Table manupulator in Linux.
(fg) Send job to foreground.
(fgrep) Search file(s) that match a fixed string.
(file) Determine file type.
(find) Search for files that meet the desired criteria.
(fmt) Reformat paragraph text.
(fold) Wrap text to fit a specified width.
(for) Expend words and execute commands.
(format) Format disks.
(free) Display memory usege.
(fsck) File system consistency checkand repair.
(ftp) Fila Transfer Protocol.
(function) Define function macros.
(fuser) Identify/kill the process that is accessing the file.
(gawk) Finds and Replaces text within file(s).
(getopts) Parse positionalparameters.
(grep) Search file(s) for lines that match the given parameters.
(groups) Print the group name of the current user.
(gunzip) Decompress file(s).
(gzip) Compress file(s).
(hash) Remembers the full pathname of a name arguement.
(head) Prints the first part of the file(s).
(help) Displays help for built-in commands.
(history) Prints Command history.
(hostname) Prints or set system name.
(id) Prints User ID and Group ID.
(ifconfig) Configure network interface.
(ifdown) Stop network interface.
(ifup) Start up a network interface.
(import) Captures an X server screen and saves the image to file.
(install) Copies files and set attributes.
(jobs) Built-in command to list active job(s).
(join) Joins the lines on a command field.
(kill) Stop a process from running.
(killall) Kills processes by name.
(less) Displays output as one screen at a time.
(let) Built-in command to perform arithmetic operations on shell variables.
(ln) Makes links b/w files.
(local) Built-in command to create variable.
(locate) Finds files.
(logname) Prints the current login name.
(logout) Built-in command to exit the current logged in shell.
(look) Displays lines beginning with a given string.
(lpc) Line printer controlprogram.
(lpr) Offline print.
(lprint) Print a file.
(lprintd) Abort a print job.
(lprintq) List a print queue.
(lprm) Remove a job from the print queue.
(ls) List file(s) and directories.
(lsof) List open file(s).
(make) Recompile a group of programs.
(man) Manual.
(mkdir) Create new directory.
(mkfifo) Make FIFOs(named pipes).
(mkisofs) Create a hybrid ISO9660/JOLIET/HFSfilesystem.
(mknod) Make block or character special files.
(mmv) Mass move/rename file(s).
(more) Displays output one screen at a time.
(mount) Mount a file system.
(mtools) Manipulate MS-DOS files.
(mtr) Network diagnostics(traceroute/ping).
(mv) Move/rename file(s)/directory.
(netstat) Network statistics/information.
(nice) Set priority of a command/job.
(nl) Number lines and write files.
(nohup) Run a command immune to hangups.
(notify-send) Send desktop notification.
(nslookup) Query internet name servers interactively.
(op) Operator access.
(open) Open a file with its default application.
(passwd) Modify User password.
(paste) Merge lines of files.
(pathchk) Check file name probability.
(ping) Test a network connection.
(pkill) Stop a process form running.
(popd) Restore the previous value ofcurrent directory.
(pr) Prepare files for printing.
(printcap) Printer capability database.
(printenv) Print environment variables.
(printf) Built-in command to print and format data.
(ps) Process status.
(pushd) Save and chande cuttent directory.
(pwd) Build-in command to print working directory.
(quota) Display disk usage and limits.
(quotacheck) Scan a file system for disk usage.
(quotactl) Set disk quotas.
(ram) Ram disk device.
(rcp) Copy files b/w two machines.
(read) Built-in command to read a line from standard input.
(readarray) Built-in command to read from stdin into an array variable.
(readonly) Mark variables/functions as readonly.
(reboot) Reboot system.
(remsync) Synchronize remote files via email.
(rename) Rename files.
(renice) Alter priority of running processes.
(return) Exit a shell function.
(rev) Reverse lines of a file.
(rm) Remove file(s).
(rmdir) Remove directories.
(rsync) Remote file copy(Synchronize file trees).
(scp) Secure copy(Remote file copy).
(screen) Multiplex terminal, run remote shells via ssh.
(sdiff) Merge two files interactively.
(sed) Stream Editor.
(select) Accept keyboard input.
(seq) Print numeric sequences.
(set) Manipulate shell variables and functions.
(sftp) Secure File Transfer Program.
(shift) Shift positional parameters.
(shopt) Shell options.
(shutdown) Shutdown system.
(sleep) Delay for a specified time.
(slocate) Find files.
(sort) Sort text files.
(source) Run command from a file.
(split) Split a fileintofixed size pieces.
(ssh) Secure Shell client(Remote login program).
(strace) Trace system calls and signals.
(su) Switch user.
(sudo) Super User DO.
(sum) Print checksum for a file.
(suspend) Build-in command to suspend execution of the shell.
(symlink) Makea new name for a file.
(sync) Synchronize data on disk with memory.
(tail) Output the last part of file.
(tar) Tape ARchive.
(tee) Redirect output to multiple files.
(test) Evaluate a conditional expression.
(time) Measure program running time.
(times) User and system times.
(top) List processes running on the system.
(touch) Change file timestamps.
(tr) Translate /squeeze /delete characters.
(traceroute) Trace route to host.
(trap) Run a command when signal is set(buorne).
(true) Do nothing successfully.
(tsort) Topological sort.
(tty) Print filename of terminal on stdin.
(type) Built-in command to describe a command.
(uiltin) Run a shell builtin.
(ulimit) Built-in command to limit user resources.
(umask) Users file creation mask.
(umount) Unmount a device.
(unalias) Built-in command to remove an alias.
(uname) Prints system information.
(unexpand) Converts spaces to tabs.
(uniq) Uniquify file(s).
(units) Convert units from one scale to another.
(unset) Remove variables/function names.
(unshar) Unpack shell archive scripts.
(until) Execute commands untill error.
(useradd) Create new user account.
(usermod) Modify user account.
(users) List users currently logged in.
(uudecode) Decode a file created by uuencode.
(uuencode) Encode a binary file.
(vdir) Verbosely display the list of directory contents
(vi) Text editor in Linux.
(vmstat) Reports virtual memory stats.
(watch) Executes/displays a program periodically.
(wc) Prints byte, word and line count.
(whereis) Does searching of users $PATH, man pages and source files of a program
(which) Does searching of users $PATH for a program file.
(while) Executes command.
(who) Prints all usernames that are currently logged in.
(whoami) Prints the current user id and name.
(write) Send a message to another user.
(xargs) Executes utility by passing constructed argument list(s).
(xdg-open) opens a file/URL in the users preferred application.
(yes) Prints a string until interrupted.
