alias       Create an alias
apropos Search Help manual pages (man -k)
awk        Find and Replace text, database sort/validate/index
break     Exit from a loop
builtin    Run a shell builtin
bzip2      Compress or decompress named file(s)
cal          Display a calendar
case       Conditionally perform a command
cat         Display the contents of a file
cd          Change Directory
cfdisk    Partition table manipulator for Linux
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 - ignoring shell functions
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 time
csplit        Split a file into context-determined pieces
cut            Divide a file into several parts
date          Display or change the date & time
dc              Desk Calculator
dd             Data Dump - Convert and copy a file
ddrescue   Data recovery tool
declare      Declare variables and give them attributes
df                Display free disk space
diff             Display the differences between two files
diff3          Show differences among three files
dig            DNS lookup
dir            Briefly list directory contents
dircolors       Colour setup for `ls’
dirname       Convert a full pathname to just a path
dirs            Display list of remembered directories
du              Estimate file space usage
echo          Display message on screen
egrep        Search file(s) for lines that match an extended expression
eject          Eject removable media
enable       Enable and disable builtin shell commands
env            Environment variables
ethtool       Ethernet card settings
eval          Evaluate several commands/arguments
exec         Execute a command
exit          Exit the shell
expand      Convert tabs to spaces
export       Set an environment variable
expr          Evaluate expressions
false          Do nothing, unsuccessfully
fdformat     Low-level format a floppy disk
fdisk           Partition table manipulator for Linux
fgrep         Search file(s) for lines that match a fixed string
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              Expand words, and execute commands
format        Format disks or tapes
free            Display memory usage
fsck          File system consistency check and repair
ftp              File Transfer Protocol
function     Define Function Macros
gawk          Find and Replace text within file(s)
getopts      Parse positional parameters
grep            Search file(s) for lines that match a given pattern
groups        Print group names a user is in
gzip            Compress or decompress named file(s)
hash          Remember the full pathname of a name argument
head           Output the first part of file(s)history Command History
hostname    Print or set system name
id             Print user and group id’s
if              Conditionally perform a command
ifconfig    Configure a network interface
import     Capture an X server screen and save the image to file
install        Copy files and set attributes
join             Join lines on a common field
kill          Stop a process from running
less         Display output one screen at a time
let          Perform arithmetic on shell variables
ln          Make links between files
local     Create variables
locate         Find files
logname    Print current login name
logout      Exit a login shell
look        Display lines beginning with a given string
lpc          Line printer control program
lpr          Off line print
lprint      Print a file
lprintd     Abort a print job
lprintq     List the print queue
lprm         Remove jobs from the print queue
ls             List information about file(s)
lsof        List open files make Recompile a group of programs
man         Help manual
mkdir      Create new folder(s)
mkfifo        Make FIFOs (named pipes)
mkisofs       Create an hybrid ISO9660/JOLIET/HFS filesystem
mknod         Make block or character special files
more          Display output one screen at a time
mount        Mount a file system
mtools          Manipulate MS-DOS files
mv Move or rename files or directories

netstat     Networking information
nice         Set the priority of a command or job
nl           Number lines and write files
nohup      Run a command immune to hangups
nslookup     Query Internet name servers interactively
passwd       Modify a user password
paste         Merge lines of files
pathchk     Check file name portability
ping          Test a network connection
popd         Restore the previous value of the current directory
pr           Prepare files for printing
printcap   Printer capability database
printenv   Print environment variables
printf        Format and print data
ps           Process status
pushd      Save and then change the current directory
pwd        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 between two machines.
read             read a line from standard input
readonly          Mark variables/functions as readonly
remsync        Synchronize remote files via email
return              Exit a shell function
rm                 Remove files
rmdir            Remove folder(s)
rsync            Remote file copy (Synchronize file trees)

screen           Terminal window manager
scp                Secure copy (remote file copy)
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 or restart linux
sleep             Delay for a specified time
sort             Sort text files
source          Run commands from a file `.’
split              Split a file into fixed-size pieces
ssh             Secure Shell client (remote login program)
strace        Trace system calls and signals
su             Substitute user identity
sum            Print a checksum for a file
symlink      Make a new name for a file
sync           Synchronize data on disk with memory
tail          Output the last part of files
tar           Tape ARchiver
tee            Redirect output to multiple files
test         Evaluate a conditional expression
time       Measure Program running time
times       User and system times
touch      Change file timestamps
top           List processes running on the system
traceroute    Trace Route to Host
trap               Run a command when a signal is set(bourne)
tr                  Translate, squeeze, and/or delete characters
true            Do nothing, successfully
tsort          Topological sort
tty              Print filename of terminal on stdin
type           Describe a command
ulimit         Limit user 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
unshar           Unpack shell archive scripts
until              Execute commands (until error)
useradd          Create new user account
usermod         Modify user account
users            List users currently logged in
uuencode       Encode a binary file
uudecode Decode a file created by uuencode

v        Verbosely list directory contents (`ls -l -b’)
vdir   Verbosely list directory contents (`ls -l -b’)
vi       Text Editor
watch       Execute/display a program periodically
wc            Print byte, word, and line counts
whereis    Report all known instances of a command
which        Locate a program file in the user’s path.
while        Execute commands
who      Print all usernames currently logged in
whoami    Print the current user id and name (`id -un’)
Wget     Retrieve web pages or files via HTTP, HTTPS or FTP
xargs    Execute utility, passing constructed argument list(s)
yes         Print a string until interrupted
.           Run a command script in the current shell
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