The linux command line--part one(一) Learing Shell

Part One Learing Shell

1.what is shell?

GNU/Linux are different things. Linux is the kernel.

[username@machinename directory] $ (a dollar sign) # means superuser privileges

command history ↑ remember the last 1000 by default

the shell is all about keyboard.

some command: df, cal, free,date.

2.Navigation

pwd - Print name of current working directory

cd - Change directory . the working directory by default .. the working directory's parent directory

some shoutcuts : cd

cd - changes the working directory to the precious working directory

cd ~username

ls - List directory contents

ls -a list all the files including hidden files.

files name are case sensitive

linux has no concept of "file extension", but many application programs do.

do not use embedded spaces ,you can use dash underscore instead.

3.Exploring the system

ls

ls ~/source

ls -l

ls -lt t order by files' modification time

ls -lt --reverse



file - Determine file type

file filename ---print a brief description of the file's content

everything is a file

less - View file contents

text

some of the programs that the system uses(called scripts)

less filename ---view the file



less is more.

In linux,there is no secrets.

Symbolic Links

lrwxrwxrwx 1 root root 11 2007-08-11 07:34 libc.so.6 -> libc-2.6.so

l

hard links

4.Manipulating Files And Directories

cp - Copy files and directories

cp item1 item2 copy the single file or directory item1 to file or directory item2

cp item... directory copy multiple items(either files or directories) into a directory







mv - Move/rename files and directories(剪切)

mv item1 item2 to move or rename file or directory "item1" to "item2"

mv item... directory to move one or more items from one directory to another

mkdir - create directories

mk directoryname

mk dir1 dir2 dir3 create three directories name dir1,dir2,dir3

rm - remove directories

be careful with rm

ln - create hard and symbolic links

ln file link to create a hand link

ln -s item link to create a symbolic link where "item" is either a file or a directory

hard link and symbolic link

Wildcard is powerful!



5.Working With Commands

type - Indicate how a command name is interpreted

type type

type ls

type cp

which - Display which executable program will be executed

which ls

which cd

help - Get help for shell builtins

help cd

mkdir --help

man - Display a command's manual page

man ls

man 5 passwd

apropos - Display a list of appropriate commands

apropos l

info - Display a command's info entry

whatis - Display a very brief description of a command

whatis ls

alias - Create an alias for a command

line trick command1; command2;command3

alias foo='cd /usr; ls; cd - '

type foo

unalias foo

type foo

alias ls

alias --list all the alias