su：Swith user  切换用户，切换到root用户
cat: Concatenate  串联
uname: Unix name  系统名称
df: Disk free  空余硬盘
du: Disk usage 硬盘使用率
chown: Change owner 改变所有者
chgrp: Change group 改变用户组
ps：Process Status  进程状态
tar：Tape archive 解压文件
chmod: Change mode 改变模式
umount: Unmount 卸载
ldd：List dynamic dependencies 列出动态相依
insmod：Install module 安装模块
rmmod：Remove module 删除模块
lsmod：List module 列表模块
alias :Create your own name for a command
bash :GNU Bourne-Again Shell  linux内核 
grep:global regular expression print
httpd :Start Apache
ipcalc :Calculate IP information for a host
ping :Send ICMP ECHO_Request to network hosts
reboot: Restart your computer
sudo:Superuser do
 
/bin = BINaries 
/dev = DEVices 
/etc = ETCetera 
/lib = LIBrary 
/proc = PROCesses 
/sbin = Superuser BINaries 
/tmp = TeMPorary 
/usr = Unix Shared Resources 
/var = VARiable 
FIFO = First In, First Out 
GRUB = GRand Unified Bootloader 
IFS = Internal Field Seperators 
LILO = LInux LOader 
MySQL = My最初作者的名字SQL = Structured Query Language 
PHP = Personal Home Page Tools = PHP Hypertext Preprocessor 
PS = Prompt String 
Perl = "Pratical Extraction and Report Language" = "Pathologically Eclectic Rubbish Lister" 
Python Monty Python's Flying Circus 
Tcl = Tool Command Language 
Tk = ToolKit 
VT = Video Terminal 
YaST = Yet Another Setup Tool 
apache = "a patchy" server 
apt = Advanced Packaging Tool 
ar = archiver 
as = assembler 
bash = Bourne Again SHell 
bc = Basic (Better) Calculator 
bg = BackGround 
cal = CALendar 
cat = CATenate 
cd = Change Directory 
chgrp = CHange GRouP 
chmod = CHange MODe 
chown = CHange OWNer 
chsh = CHange SHell 
cmp = compare 
cobra = Common Object Request Broker Architecture 
comm = common 
cp = CoPy 
cpio = CoPy In and Out 
cpp = C Pre Processor 
cups = Common Unix Printing System 
cvs = Current Version System 
daemon = Disk And Execution MONitor 
dc = Desk Calculator 
dd = Disk Dump 
df = Disk Free 
diff = DIFFerence 
dmesg = diagnostic message 
ed = editor 
egrep = Extended GREP 
elf = Extensible Linking Format 
elm = ELectronic Mail 
emacs = Editor MACroS 
eval = EVALuate 
ex = EXtended 
exec = EXECute 
fd = file descriptors 
fg = ForeGround 
fgrep = Fixed GREP 
fmt = format 
fsck = File System ChecK 
fstab = FileSystem TABle 
fvwm = F*** Virtual Window Manager 
gawk = GNU AWK 
gpg = GNU Privacy Guard 
groff = GNU troff 
hal = Hardware Abstraction Layer 
joe = Joe's Own Editor 
ksh = Korn SHell 
lame = Lame Ain't an MP3 Encoder 
lex = LEXical analyser 
lisp = LISt Processing = Lots of Irritating Superfluous Parentheses 
ln = LiNk 
lpr = Line PRint 
ls = list 
lsof = LiSt Open Files 
m4 = Macro processor Version 4 
man = MANual pages 
mawk = Mike Brennan's AWK 
mc = Midnight Commander 
mkfs = MaKe FileSystem 
mknod = MaKe NODe 
motd = Message of The Day 
mozilla = MOsaic GodZILLa 
mtab = Mount TABle 
mv = MoVe 
nano = Nano's ANOther editor 
nawk = New AWK 
nl = Number of Lines 
nm = names 
nohup = No HangUP 
nroff = New ROFF 
od = Octal Dump 
passwd = PASSWorD 
pg = pager 
pico = PIne's message COmposition editor 
pine = "Program for Internet News & Email" = "Pine is not Elm" 
ping =  Packet InterNet Grouper 
pirntcap = PRINTer CAPability 
popd = POP Directory 
pr = pre 
printf = PRINT Formatted 
pty = pseudo tty 
pushd = PUSH Directory 
pwd = Print Working Directory 
rc = runcom = run command, shell 
rev = REVerse 
rm = ReMove 
rn = Read News 
roff = RunOFF 
rpm = RPM Package Manager = RedHat Package Manager 
rsh, rlogin, = Remote 
rxvt = ouR XVT 
sed = Stream EDitor 
seq = SEQuence 
shar = SHell ARchive 
slrn = S-Lang rn 
ssh = Secure SHell 
ssl = Secure Sockets Layer 
stty = Set TTY 
su = Substitute User 
svn = SubVersioN 
tcsh = TENEX C shell 
telnet = TEminaL over Network 
termcap = terminal capability 
terminfo = terminal information 
tr = traslate 
troff = Typesetter new ROFF 
tsort = Topological SORT 
tty = TeleTypewriter 
twm = Tom's Window Manager 
tz = TimeZone 
udev = Userspace DEV 
ulimit = User's LIMIT 
umask = User's MASK 
uniq = UNIQue 
vi = VIsual = Very Inconvenient 
vim = Vi IMproved