Login:

login: <user account>

password: <user password>

Logout:

logout
exit

Ctrl-D

File Systems:

pwd: print current working directory

ls [-l] [-a]: List the contents of current directory

File attributes:

drwxr-xr-x  2 root  root  1024 Jun 4 17:01 bin/

• d: [-dlsbc] -> [file,directory,link,special,block,char]

• permission modes:
  • user (owner)        read
  • group                     write
  • others                   execute

• Change permission mode of files or directories:
  • chmod <mode> <filenames>
  • <mode>: [ugo][+-][rwx] or an octal number

• Change owner of files
  • chown <user>.<group> <filenames>

Linux system directories:

/                           root directory

/bin                      binary files

/dev                     device files

/etc                      configuration files and initialization scripts

/home                  root of user home directories

/lib                       programming language library

/lost+found         lost files

/proc                    Linux system information

/root                     root home directory

/sbin                     binary files for system management

/tmp                     temporary directory

/usr                      user files

/var                      various files

/mnt                     a temporary mount point

Special directories:

~                 : home directory

~<user>      : home directory of <user>

.                  : current directory

..                 : parent directory

Directory-related commands:

cd <directory>          : change directory

mkdir <directory>    : make directory

rmdir <directory>    : remove directory

File-related commands:

cp <filename> <destination>        : copy files

mv <filename> <destination>       : move or rename files

rm <filename>                               : remove files

more <filename>                           : display file by page

cat <filename>                              : display the whole file

ln [-s] <oldname> <newname>   : make links to files

I/O redirection:

<     : input

>     : output

|      : pipe

Online manual pages:

man <command>: display manual page for <command>

User Info

User information commands:

who                        : display who is logged in on the system

w                            : display who is logged in, and what are they doing

whoami                  : display current user name

finger <user>         : display information about <user>

Changing user information:

passwd    : change password

chsh         : change shell

chfn  &nb

sp;    &
nbsp;

: change finger information

Process & Job Control

Terminating processes or jobs:

Ctrl-C: interrupt current process

Ctrl-D: terminate file input

Ctrl-Z: suspend current process

Process-related commands:

ps [-x] [-a]: display information of processes

kill -9 <PID>

Job control:

<command> &      : run command in background

bg                           : put current suspended job into background running

fg                            : continue suspended job

jobs                         : list background jobs

Alias:

alias <name> = <command line>         : assign command line to the alias

unalias <name>                            : remove alias

File Editors: joe, vi, ed, emacs, pico, …

• Basic operation of joe:

Ctrl-KX: save file and quit

Ctrl-C: quit

Ctrl-KB: mark beginning

Ctrl-KK: mark End

Ctrl-KC: copy marked text

Ctrl-KM: move marked text

·         Basic operation of vi:

(1)    In command mode:

arrow keys    change cursor position

i                    insert (change into editing mode)

a                   append after cursor (change into editing mode)

x                   delete this character

dd                 delete this line

:w                 write to file

:q                  quit

:q!                 quit without saving changes

(2)    In editing mode:

ESC              change back to command mode

Printing commands:

lpr <file>   : print a file

lpq              : list printer queue

lprm [-]      : remove a printing job

Miscellaneous commands:

clear                             : clear screen

date                              : display current date and time

which <command>     : display the pathname of <command>

Environment variables:

set                                                         : display current environment variables

echo $PATH                                        : display current setting of PATH

<name>=<value>; export <name>   : define a variable <name>

Shell scripts ó batch files in DOS

Local Configuration Files:

~/.cshrc         : C Shell rc file

~/.login          : Login scripts

~/.plan           : personal plan à for finger

~/.forward     : e-mail forward list

Becoming superuser:

su <root>
sudo <command>

Useful tools:

find <dir> [-name <filename>] [-print]            : find <filename> from <dir>

grep <string> <files>                             : search <string> in <files>

diff <file1> <file2>                                 : display the differences between <file1> and <file2>