In this part,I will show you how to do some arithmetic calculation in Bash.
1.COMMAND:
expr
DESCRIPTION:
Print the value of EXPRESSION to standard output.
SYNOPSIS:
expr EXPRESSION
Example:
root@piniheaven:~# expr 1 + 1
2
root@piniheaven:~# expr 2 - 1
1
root@piniheaven:~# expr 4 / 2
2
root@piniheaven:~# expr 2 \* 2 #Tip: when you want to do some multiplication,you should use backslash
4
2.COMMAND:
let
DESCRIPTION:
carry out arithmetic operations on variables.
Example:
root@piniheaven:~# let " val=(1+1)*2" # will compute 2 times 2 and assign the result to the variable "val".
root@piniheaven:~# echo $val #print variable val
4
2014年3月19日星期三
Linux Commands for Beginners lesson 18 -- Finding Files
In this part, I demonstrate how to find files.
1.COMMAND:
find
DESCRIPTION:
search for files in a directory hierarchy
SYNOPSIS:
find <path> <fileName>
OPTION:
-mtime n File's data was last modified n*24 hours ago.
-name Base of file name
Example:
If you remember the file's name,you can specify a path to find it out.
root@piniheaven:~# find /root/ -name find.txt
/root/tutorial/find.txt
Even you can't remember what the exactly file name is,you still can find it out.
root@piniheaven:~# find /root/ -name fin*
/root/tutorial/find.txt
Find out files that was last modified 24 hours ago.
root@piniheaven:~# find /root/tutorial/ -mtime -1
/root/tutorial/
/root/tutorial/.find.txt.swp
/root/tutorial/poem.txt
/root/tutorial/find.txt
1.COMMAND:
find
DESCRIPTION:
search for files in a directory hierarchy
SYNOPSIS:
find <path> <fileName>
OPTION:
-mtime n File's data was last modified n*24 hours ago.
-name Base of file name
Example:
If you remember the file's name,you can specify a path to find it out.
root@piniheaven:~# find /root/ -name find.txt
/root/tutorial/find.txt
Even you can't remember what the exactly file name is,you still can find it out.
root@piniheaven:~# find /root/ -name fin*
/root/tutorial/find.txt
Find out files that was last modified 24 hours ago.
root@piniheaven:~# find /root/tutorial/ -mtime -1
/root/tutorial/
/root/tutorial/.find.txt.swp
/root/tutorial/poem.txt
/root/tutorial/find.txt
Linux Commands for Beginners lesson 17 -- Head and Tail Command
In this part, I go over both the head and tail commands.
1.COMMAND:
head
DESCRIPTION:
Print the first 10 lines of FILE to standard output.
SYNOPSIS:
head [OPTION]... [FILE]...
OPTION:
-n, --lines
print the first n lines instead of the first 10;
2.COMMAND:
tail
DESCRIPTION:
Print the last 10 lines of FILE to standard output.
SYNOPSIS:
tail [OPTION]... [FILE]...
OPTION:
-n, --lines output the last K lines, instead of the last 10;
Examples:
root@piniheaven:~/tutorial# ls
poem.txt
root@piniheaven:~/tutorial# head poem.txt # Print the first 10 lines of poem.txt to standard output.
nt you to know
one thing.
You know how this is:
if I look
at the crystal moon, at the red branch
of the slow autumn at my window,
if I touch
near the fire
the impalpable ash
root@piniheaven:~/tutorial# head -4 poem.txt # Print the first 4 lines of poem.txt to standard output.
nt you to know
one thing.
You know how this is:
root@piniheaven:~/tutorial# tail poem.txt # Print the last 10 lines of poem.txt to standard output.
you feel that you are destined for me
with implacable sweetness,
if each day a flower
climbs up to your lips to seek me,
ah my love, ah my own,
in me all that fire is repeated,
in me nothing is extinguished or forgotten,
my love feeds on your love, beloved,
and as long as you live it will be in your arms
without leaving mine
root@piniheaven:~/tutorial# tail -3 poem.txt # Print the last 3 lines of poem.txt to standard output.
my love feeds on your love, beloved,
and as long as you live it will be in your arms
without leaving mine
1.COMMAND:
head
DESCRIPTION:
Print the first 10 lines of FILE to standard output.
SYNOPSIS:
head [OPTION]... [FILE]...
OPTION:
-n, --lines
print the first n lines instead of the first 10;
2.COMMAND:
tail
DESCRIPTION:
Print the last 10 lines of FILE to standard output.
SYNOPSIS:
tail [OPTION]... [FILE]...
OPTION:
-n, --lines output the last K lines, instead of the last 10;
Examples:
root@piniheaven:~/tutorial# ls
poem.txt
root@piniheaven:~/tutorial# head poem.txt # Print the first 10 lines of poem.txt to standard output.
nt you to know
one thing.
You know how this is:
if I look
at the crystal moon, at the red branch
of the slow autumn at my window,
if I touch
near the fire
the impalpable ash
root@piniheaven:~/tutorial# head -4 poem.txt # Print the first 4 lines of poem.txt to standard output.
nt you to know
one thing.
You know how this is:
root@piniheaven:~/tutorial# tail poem.txt # Print the last 10 lines of poem.txt to standard output.
you feel that you are destined for me
with implacable sweetness,
if each day a flower
climbs up to your lips to seek me,
ah my love, ah my own,
in me all that fire is repeated,
in me nothing is extinguished or forgotten,
my love feeds on your love, beloved,
and as long as you live it will be in your arms
without leaving mine
root@piniheaven:~/tutorial# tail -3 poem.txt # Print the last 3 lines of poem.txt to standard output.
my love feeds on your love, beloved,
and as long as you live it will be in your arms
without leaving mine
Linux Commands for Beginners lesson 16 -- The Watch Command
In this part, I talk about the watch command.
DESCRIPTION :
execute a program periodically, showing output fullscreen
SYNOPSIS :
watch [option] <command>
OPTION :
-n : By default, the program is run every 2 seconds; use -n to specify a different interval.
command: any linux command you want to type
Example :
[piniheaven@localhost ~]$ watch -n 10 free -m #Every 10.0s free -mwill be executed automatically
Every 10.0s: free -m Tue Sep 3 17:48:56 2013
total used free shared buffers cached
Mem: 5690 1388 4301 0 82 620
-/+ buffers/cache: 685 5004
Swap: 0 0 0
1.COMMAND :
watchDESCRIPTION :
execute a program periodically, showing output fullscreen
SYNOPSIS :
watch [option] <command>
OPTION :
-n : By default, the program is run every 2 seconds; use -n to specify a different interval.
command: any linux command you want to type
Example :
[piniheaven@localhost ~]$ watch -n 10 free -m #Every 10.0s free -mwill be executed automatically
Every 10.0s: free -m Tue Sep 3 17:48:56 2013
total used free shared buffers cached
Mem: 5690 1388 4301 0 82 620
-/+ buffers/cache: 685 5004
Swap: 0 0 0
Linux Commands for Beginners lesson 15 -- du,df,free commands
In this part, I talk about viewing system resources.
1.COMMAND :
df
DESCRIPTON :
report file system disk space usage
SYNOPSIS :
df [OPTION]... [FILE]...
OPTION :
-h, --human-readable
Example :
[piniheaven@localhost ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 15G 5.4G 9.0G 38% /
tmpfs 2.8G 884K 2.8G 1% /dev/shm
2.COMMAND :
du
DESCRIPTION :
estimate file space
SYNOPSIS :
du [OPTION]... [FILE]...
OPTION :
-s, --summarize
display only a total for each argument
-h, --human-readable print sizes in human readable format (e.g., 1K 234M 2G)
Example :
[piniheaven@localhost ~]$ ls
Desktop Documents Music Public SolftWare tutorial
distribute-0.6.49 Downloads Pictures Python-2.7.3 Templates Videos
[piniheaven@localhost ~]$ du -sh Videos
254MVideos
3.COMMAND :
free
DESCRIPTION :
Display amount of free and used memory in the system
SYNOPSIS :
free [-m]
OPTION :
-m switch displays it in megabytmegabytes.
Example :
[piniheaven@localhost ~]$ free-m
total used free shared buffers cached
Mem: 5690 1736 3953 0 74 615
-/+ buffers/cache: 1046 4644
Swap: 0 0 0
Explanation:
Actual Used Physical Memory (Memory Used by Apps) :1046 MB
Actual Free Physical Memory (Memory Available For Apps) :4644 MB
1.COMMAND :
df
DESCRIPTON :
report file system disk space usage
SYNOPSIS :
df [OPTION]... [FILE]...
OPTION :
-h, --human-readable
Example :
[piniheaven@localhost ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 15G 5.4G 9.0G 38% /
tmpfs 2.8G 884K 2.8G 1% /dev/shm
2.COMMAND :
du
DESCRIPTION :
estimate file space
SYNOPSIS :
du [OPTION]... [FILE]...
OPTION :
-s, --summarize
display only a total for each argument
-h, --human-readable print sizes in human readable format (e.g., 1K 234M 2G)
Example :
[piniheaven@localhost ~]$ ls
Desktop Documents Music Public SolftWare tutorial
distribute-0.6.49 Downloads Pictures Python-2.7.3 Templates Videos
[piniheaven@localhost ~]$ du -sh Videos
254MVideos
3.COMMAND :
free
DESCRIPTION :
Display amount of free and used memory in the system
SYNOPSIS :
free [-m]
OPTION :
-m switch displays it in megabytmegabytes.
Example :
[piniheaven@localhost ~]$ free-m
total used free shared buffers cached
Mem: 5690 1736 3953 0 74 615
-/+ buffers/cache: 1046 4644
Swap: 0 0 0
Explanation:
Actual Used Physical Memory (Memory Used by Apps) :1046 MB
Actual Free Physical Memory (Memory Available For Apps) :4644 MB
If you want to know more about what is the difference between buffer and cache memory,you can click following link.
Linux Commands for Beginners lesson 14 -- the grep command
In this part,I wil show you the basis of Regular Expressions and the grep command
1.Command:
grep
DESCRIPTION:
print lines matching a pattern
SYNOPSIS:
grep [OPTIONS] PATTERN [FILE...]
OPTION:
-n, --line-number print line number with output lines
Regular expressions made up of anchors,character sets,modifiers
Anchors:specify the position
^ :at the beginnig of a line
$ :at the end of a line
Tips:If ^ is not placed at the beginning ,or $ at the end,the two won't act as anchors anymore
character sets:what is seached
Example:
root@piniheaven:~/tutorial# ls
A Girl.txt
root@piniheaven:~/tutorial# cat -n A\ Girl.txt
1 the tree has entered my hands
2 the sap has ascended my arms
3 the tree has grown in my breast-
4 downward
5 the branches grow out of me, like arms
6
7 tree you are
8 moss you are
9 you are violets with wind above them
10 a child - so high - you are
11 and all this is folly to the world
print lines contain words "tree"
root@piniheaven:~/tutorial# grep 'tree' A\ Girl.txt
the tree has entered my hands
the tree has grown in my breast-
tree you are
print lines contain word "tree" and print which line they are in
root@piniheaven:~/tutorial# grep -n 'tree' A\ Girl.txt
1:the tree has entered my hands
3:the tree has grown in my breast-
7:tree you are
print lines start with word "tree" and print which line they are in
root@piniheaven:~/tutorial# grep -n ^'tree' A\ Girl.txt
7:tree you are
print lines contain word "are" and print which line they are in
root@piniheaven:~/tutorial# grep -n 'are' A\ Girl.txt
7:tree you are
8:moss you are
9:you are violets with wind above them
10:a child - so high - you are
print lines end with word "are" and print which line they are in
root@piniheaven:~/tutorial# grep -n 'are'$ A\ Girl.txt
7:tree you are
8:moss you are
10:a child - so high - you are
Matching Character Sets
--"abc" finds lines with "abc" in them
--match any character with "."(dot)
--specify a range with []
[123] - lines that contain 1,2 or 3
[0-9] - lines that contain at least a number
[A-Za-z0-9] - lines that contain at leas a letters or a numbers
Example:
Find words start with letter 'm' and follow with a any character
root@piniheaven:~/tutorial# grep -n 'm.' A\ Girl.txt
1:the tree has entered my hands
2:the sap has ascended my arms
3:the tree has grown in my breast-
5:the branches grow out of me, like arms
8:moss you are
Find words start with letter 'a' or 'b'
root@piniheaven:~/tutorial# grep -n ^'[ad]' A\ Girl.txt
4:downward
10:a child - so high - you are
11:and all this is folly to the world
print lines start with a letter range from 'a' to 'm'
root@piniheaven:~/tutorial# grep -n ^'[a-m]' A\ Girl.txt
4:downward
8:moss you are
10:a child - so high - you are
11:and all this is folly to the world
Tips:
If you want to search for "[" or "]",you should use backslash "\"
Example:
[\]] - search lines with "]" in them
modifiers:specify how many times the previous charater set is repeated
* - matches zero or more copies of the chars
[]\{1,4\} - lines that have between 1 to 4 mathes
\<word\> - searches for a specific and separate word
Example:
root@piniheaven:~/tutorial# ls
A Girl.txt essay.txt
root@piniheaven:~/tutorial# cat -n essay.txt
1 a
2 aa
3 aaa
4 aaaa
5 aaaaa
6 aaaaaa
7
8 abc
9 abbc
10 abcc
print lines contain word that mach [b-c][b-c]
root@piniheaven:~/tutorial# grep -n '[b-c]\{2,3\}' essay.txt
8:abc
9:abbc
10:abcc
If you want to just search specify word,following command failed to work.
root@piniheaven:~/tutorial# grep -n 'aa' essay.txt
2:aa
3:aaa
4:aaaa
5:aaaaa
6:aaaaaa
therefore,you can type command like this
root@piniheaven:~/tutorial# grep -n '\<aa\>' essay.txt
2:aa
1.Command:
grep
DESCRIPTION:
print lines matching a pattern
SYNOPSIS:
grep [OPTIONS] PATTERN [FILE...]
OPTION:
-n, --line-number print line number with output lines
Regular expressions made up of anchors,character sets,modifiers
Anchors:specify the position
^ :at the beginnig of a line
$ :at the end of a line
Tips:If ^ is not placed at the beginning ,or $ at the end,the two won't act as anchors anymore
character sets:what is seached
Example:
root@piniheaven:~/tutorial# ls
A Girl.txt
root@piniheaven:~/tutorial# cat -n A\ Girl.txt
1 the tree has entered my hands
2 the sap has ascended my arms
3 the tree has grown in my breast-
4 downward
5 the branches grow out of me, like arms
6
7 tree you are
8 moss you are
9 you are violets with wind above them
10 a child - so high - you are
11 and all this is folly to the world
print lines contain words "tree"
root@piniheaven:~/tutorial# grep 'tree' A\ Girl.txt
the tree has entered my hands
the tree has grown in my breast-
tree you are
print lines contain word "tree" and print which line they are in
root@piniheaven:~/tutorial# grep -n 'tree' A\ Girl.txt
1:the tree has entered my hands
3:the tree has grown in my breast-
7:tree you are
print lines start with word "tree" and print which line they are in
root@piniheaven:~/tutorial# grep -n ^'tree' A\ Girl.txt
7:tree you are
print lines contain word "are" and print which line they are in
root@piniheaven:~/tutorial# grep -n 'are' A\ Girl.txt
7:tree you are
8:moss you are
9:you are violets with wind above them
10:a child - so high - you are
print lines end with word "are" and print which line they are in
root@piniheaven:~/tutorial# grep -n 'are'$ A\ Girl.txt
7:tree you are
8:moss you are
10:a child - so high - you are
Matching Character Sets
--"abc" finds lines with "abc" in them
--match any character with "."(dot)
--specify a range with []
[123] - lines that contain 1,2 or 3
[0-9] - lines that contain at least a number
[A-Za-z0-9] - lines that contain at leas a letters or a numbers
Example:
Find words start with letter 'm' and follow with a any character
root@piniheaven:~/tutorial# grep -n 'm.' A\ Girl.txt
1:the tree has entered my hands
2:the sap has ascended my arms
3:the tree has grown in my breast-
5:the branches grow out of me, like arms
8:moss you are
Find words start with letter 'a' or 'b'
root@piniheaven:~/tutorial# grep -n ^'[ad]' A\ Girl.txt
4:downward
10:a child - so high - you are
11:and all this is folly to the world
print lines start with a letter range from 'a' to 'm'
root@piniheaven:~/tutorial# grep -n ^'[a-m]' A\ Girl.txt
4:downward
8:moss you are
10:a child - so high - you are
11:and all this is folly to the world
Tips:
If you want to search for "[" or "]",you should use backslash "\"
Example:
[\]] - search lines with "]" in them
modifiers:specify how many times the previous charater set is repeated
* - matches zero or more copies of the chars
[]\{1,4\} - lines that have between 1 to 4 mathes
\<word\> - searches for a specific and separate word
Example:
root@piniheaven:~/tutorial# ls
A Girl.txt essay.txt
root@piniheaven:~/tutorial# cat -n essay.txt
1 a
2 aa
3 aaa
4 aaaa
5 aaaaa
6 aaaaaa
7
8 abc
9 abbc
10 abcc
print lines contain word that mach [b-c][b-c]
root@piniheaven:~/tutorial# grep -n '[b-c]\{2,3\}' essay.txt
8:abc
9:abbc
10:abcc
If you want to just search specify word,following command failed to work.
root@piniheaven:~/tutorial# grep -n 'aa' essay.txt
2:aa
3:aaa
4:aaaa
5:aaaaa
6:aaaaaa
therefore,you can type command like this
root@piniheaven:~/tutorial# grep -n '\<aa\>' essay.txt
2:aa
Linux Commands for Beginners lesson 13-- which and whatis commands
In this tutorial, I talk about the which and whatis commands.
1.COMMAND:
which
DESCRIPTION:
locate a command
SYNOPSIS
which commandName
Example:
piniheaven@fish:~$ which ls
/bin/ls
piniheaven@fish:~$ which nano
/usr/bin/nano
2.COMMAND:
whatis
DESCRIPTION:
display manual page descriptions
SYNOPSIS
whatis commandName
Example:
piniheaven@fish:~$ whatis firefox
firefox (1) - a free and open source web browser from Mozilla
piniheaven@fish:~$ whatis ls
ls (1) - list directory contents
1.COMMAND:
which
DESCRIPTION:
locate a command
SYNOPSIS
which commandName
Example:
piniheaven@fish:~$ which ls
/bin/ls
piniheaven@fish:~$ which nano
/usr/bin/nano
2.COMMAND:
whatis
DESCRIPTION:
display manual page descriptions
SYNOPSIS
whatis commandName
Example:
piniheaven@fish:~$ whatis firefox
firefox (1) - a free and open source web browser from Mozilla
piniheaven@fish:~$ whatis ls
ls (1) - list directory contents
Linux Commands for Beginners lesson 12 -- Create Your Own Commands Via alias
In this part, I will show you how to create your own commands via alias
1.COMMAND:
alias
DESCRIPTION:
The alias command can be useful if you want to create a 'shortcut' to a command.
SYNOPSIS:
alias name='command'
TIPS:
To see a list of aliases set up on your linux, just type alias at the prompt.
Example:
piniheaven@fish:~/Documents$alias #list aliases set up on your system
alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
alias egrep='egrep --color=auto'
alias fgrep='fgrep --color=auto'
alias grep='grep --color=auto'
alias l='ls -CF'
alias la='ls -A'
alias ll='ls -alF'
piniheaven@fish:~/Documents$ aliasMyLs='ls -l' #create an alias of 'ls -l'
piniheaven@fish:~/Documents$ ls
assemble C++primer_ex C++primer_note Ebook linux MyScript QT_ex QT_note tutorial
piniheaven@fish:~/Documents$ MyLs
total 36
drwxrwxr-x 4 piniheaven piniheaven 4096 Aug 22 12:16 assemble
drwxrwxr-x 2 piniheaven piniheaven 4096 Jul 19 14:12 C++primer_ex
dr-xr-xr-x 2 jack piniheaven 4096 Aug 25 21:42 tutorial
DESCRIPTION:
unalias command is used to remove an alias (see alias).
SYNOPSIS:
unalias commandName
Example:
piniheaven@fish:~/Documents$ unalias MyLs #unalias Myls command
piniheaven@fish:~/Documents$ MyLs
MyLs: command not found
1.COMMAND:
alias
DESCRIPTION:
The alias command can be useful if you want to create a 'shortcut' to a command.
SYNOPSIS:
alias name='command'
TIPS:
To see a list of aliases set up on your linux, just type alias at the prompt.
Example:
piniheaven@fish:~/Documents$alias #list aliases set up on your system
alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
alias egrep='egrep --color=auto'
alias fgrep='fgrep --color=auto'
alias grep='grep --color=auto'
alias l='ls -CF'
alias la='ls -A'
alias ll='ls -alF'
alias ls='ls --color=auto'
piniheaven@fish:~/Documents$ ls
assemble C++primer_ex C++primer_note Ebook linux MyScript QT_ex QT_note tutorial
piniheaven@fish:~/Documents$ MyLs
total 36
drwxrwxr-x 4 piniheaven piniheaven 4096 Aug 22 12:16 assemble
drwxrwxr-x 2 piniheaven piniheaven 4096 Jul 19 14:12 C++primer_ex
......
......
drwxrwxr-x 2 piniheaven piniheaven 4096 Jul 19 00:21 QT_notedr-xr-xr-x 2 jack piniheaven 4096 Aug 25 21:42 tutorial
2.COMMAND:
unaliasDESCRIPTION:
unalias command is used to remove an alias (see alias).
SYNOPSIS:
unalias commandName
Example:
piniheaven@fish:~/Documents$ unalias MyLs #unalias Myls command
piniheaven@fish:~/Documents$ MyLs
MyLs: command not found
Linux Commands for Beginners lesson 11 -- Creating Your First Scripting
In this part, I give you an introduction to scripting.
piniheaven@fish:~/Documents$ cat MyScript
#!/bin/bash
#specify using bash shell
#you can create any linux command here
ls
Hello="Hello,my first scripting!"
echo $Hello
Step 2: give MyScript execute permission
piniheaven@fish:~/Documents$ chmod u+x MyScript
piniheaven@fish:~/Documents$ ls -l
total 36
drwxrwxr-x 4 piniheaven piniheaven 4096 Aug 22 12:16 assemble
......
......
-rwxrw-r-- 1 piniheaven piniheaven 146 Aug 27 17:02 MyScript
dr-xr-xr-x 2 jack piniheaven 4096 Aug 25 21:42 tutorial
assemble C++primer_exC++primer_noteEbook linux MyScriptQT_ex QT_notetutorial
Hello,my first scripting!
Example:
Step1: create a scripting
piniheaven@fish:~/Documents$nano MyScript piniheaven@fish:~/Documents$ cat MyScript
#!/bin/bash
#specify using bash shell
#you can create any linux command here
ls
Hello="Hello,my first scripting!"
echo $Hello
Step 2: give MyScript execute permission
piniheaven@fish:~/Documents$ chmod u+x MyScript
piniheaven@fish:~/Documents$ ls -l
total 36
drwxrwxr-x 4 piniheaven piniheaven 4096 Aug 22 12:16 assemble
......
......
-rwxrw-r-- 1 piniheaven piniheaven 146 Aug 27 17:02 MyScript
dr-xr-xr-x 2 jack piniheaven 4096 Aug 25 21:42 tutorial
Step 3: execute MyScript
piniheaven@fish:~/Documents$./MyScript assemble C++primer_exC++primer_noteEbook linux MyScriptQT_ex QT_notetutorial
Hello,my first scripting!
Linux Commands for Beginners lesson 10 -- Echo And Creating Variables
In this part, I introduce the echo command as well as creating variables.
This tutorial is pretty easy,but very important to bash scripting which I will introduce in following tutorials.
1.COMMAND:
echo
DESCRIPTION:
display a line of text
SYNOPSIS:
echo string
Example:
piniheaven@fish:~/Documents$ echo"Hello,CSDN"
Hello,CSDN
2.Creating variable and calling variable
Example:
piniheaven@fish:~/Documents$ Hello="Hello,CSDN" #create variable
piniheaven@fish:~/Documents$ echo$Hello #call variable
Hello,CSDN
This tutorial is pretty easy,but very important to bash scripting which I will introduce in following tutorials.
1.COMMAND:
echo
DESCRIPTION:
display a line of text
SYNOPSIS:
echo string
Example:
piniheaven@fish:~/Documents$ echo"Hello,CSDN"
Hello,CSDN
2.Creating variable and calling variable
Example:
piniheaven@fish:~/Documents$ Hello="Hello,CSDN" #create variable
piniheaven@fish:~/Documents$ echo$Hello #call variable
Hello,CSDN
Linux Commands for Beginners lesson 9 -- chmod command
In this part, I go over changing permissions of files and folders.
1.COMMAND:
chmod
DESCRIPTION:
change file mode bits
SYNOPSIS:
chmod [OPTION] [ugoa][+-=][rwx] FILE
OPTION:
-R recursive, include objects in subdirectories
u user the owner of the file
g groupusers who are members of the file's group
o othersusers who are neiter the owner of the file nor members of the file's group
a allall three of the above, same as ugo
+ adds the specified modes to the specified classes
- removes the specified modes from the specified classes
= the modes specified are to be made the exact modes for the specified classes
r read read a file or list a directory's contents
w writewrite to a file or directory
x executeexecute a file or recurse a directory tree
Example:
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rw-rw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudo chmod u+x essay.txt #give user the permission to execute essay.txt
[sudo] password for piniheaven:
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rwxrw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudo chmodu-r essay.txt #remove user's permission of reading essay.txt
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
--wxrw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudochmod uo+r essay.txt#give user and others the permission of reading essay.txt
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rwxrw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudo chmod a=x essay.txt #assign user,group and others only the permission to execute essay.txt
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
---x--x--x 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$sudo chmodugo+rwx essay.txt #assign user,group and others with the permission of read,write and excute
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rwxrwxrwx 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ cd ..piniheaven@fish:~/Documents$sudo chmod -R a=rx tutorial #assign user,group and others with the permission of read and excute, including it's subdirectories
piniheaven@fish:~/Documents$ ls -l
total 32
drwxrwxr-x 4 piniheaven piniheaven 4096 Aug 22 12:16 assemble
......
......
dr-xr-xr-x 2 jack piniheaven 4096 Aug 25 21:42 tutorial
piniheaven@fish:~/Documents$ ls -l tutorial/
total 0
-r-xr-xr-x 1 jack piniheaven 0 Aug 25 21:42 essay.txt
1.COMMAND:
chmod
DESCRIPTION:
change file mode bits
SYNOPSIS:
chmod [OPTION] [ugoa][+-=][rwx] FILE
OPTION:
-R recursive, include objects in subdirectories
u user the owner of the file
g groupusers who are members of the file's group
o othersusers who are neiter the owner of the file nor members of the file's group
a allall three of the above, same as ugo
+ adds the specified modes to the specified classes
- removes the specified modes from the specified classes
= the modes specified are to be made the exact modes for the specified classes
r read read a file or list a directory's contents
w writewrite to a file or directory
x executeexecute a file or recurse a directory tree
If you have any problem in reading following example,maybe you need to know more about file permission.Want more information?You can click my previous tutorial File Permission
Example:
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rw-rw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudo chmod u+x essay.txt #give user the permission to execute essay.txt
[sudo] password for piniheaven:
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rwxrw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudo chmodu-r essay.txt #remove user's permission of reading essay.txt
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
--wxrw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudochmod uo+r essay.txt#give user and others the permission of reading essay.txt
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rwxrw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ sudo chmod a=x essay.txt #assign user,group and others only the permission to execute essay.txt
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
---x--x--x 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$sudo chmodugo+rwx essay.txt #assign user,group and others with the permission of read,write and excute
piniheaven@fish:~/Documents/tutorial$ ls -l
total 0
-rwxrwxrwx 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents/tutorial$ cd ..piniheaven@fish:~/Documents$sudo chmod -R a=rx tutorial #assign user,group and others with the permission of read and excute, including it's subdirectories
piniheaven@fish:~/Documents$ ls -l
total 32
drwxrwxr-x 4 piniheaven piniheaven 4096 Aug 22 12:16 assemble
......
......
dr-xr-xr-x 2 jack piniheaven 4096 Aug 25 21:42 tutorial
piniheaven@fish:~/Documents$ ls -l tutorial/
total 0
-r-xr-xr-x 1 jack piniheaven 0 Aug 25 21:42 essay.txt
Linux Commands for Beginners lesson 8 -- chown command
In this part, we'll learn how to change ownership of files and folders.
1.COMMAND:
chown
DESCRIPTION:
change file owner and group
SYNOPSIS
chown [OPTION]... [OWNER][:[GROUP]] FILE...
OPTION:
-R, --recursive
operate on files and directories recursively
Example:
piniheaven@fish:~/Documents$ls
assemble C++primer_ex C++primer_note Ebook linux QT_ex QT_note tutorial
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 piniheaven piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents$ sudochown jack ./tutorial/essay.txt #change essay.txt's owner
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents$ sudochown piniheaven:Students ./tutorial/essay.txt #change essay.txt's owner and group
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 piniheaven Students 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents$ sudochown -R jack:piniheaven ./tutorial #change all files's owner and group in tutorial directory
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
1.COMMAND:
chown
DESCRIPTION:
change file owner and group
SYNOPSIS
chown [OPTION]... [OWNER][:[GROUP]] FILE...
OPTION:
-R, --recursive
operate on files and directories recursively
Example:
piniheaven@fish:~/Documents$ls
assemble C++primer_ex C++primer_note Ebook linux QT_ex QT_note tutorial
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 piniheaven piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents$ sudochown jack ./tutorial/essay.txt #change essay.txt's owner
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents$ sudochown piniheaven:Students ./tutorial/essay.txt #change essay.txt's owner and group
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 piniheaven Students 0 Aug 25 21:42 essay.txt
piniheaven@fish:~/Documents$ sudochown -R jack:piniheaven ./tutorial #change all files's owner and group in tutorial directory
piniheaven@fish:~/Documents$ ls -l ./tutorial/
total 0
-rw-rw-r-- 1 jack piniheaven 0 Aug 25 21:42 essay.txt
Linux Commands for Beginners lesson 7 -- userdel command
In this part, I will show you how to remove users from your Linux system.
1. COMMAND：
userdelDESCRIPTON：
delete a user account and related files
SYNOPSIS
userdel [options] LOGIN
OPTION:
-r, --remove
Files in the user's home directory will be removed along with the
home directory itself and the user's mail spool.
Example:
piniheaven@fish:~$ ls /home
jack piniheaven tom
piniheaven@fish:~$ sudouserdel jack #delete user account,but not delete files in the user's home directory
piniheaven@fish:~$ ls /home
jack piniheaven tom
piniheaven@fish:~$ sudouserdel -r tom #delete user account,and delete files in the user's home directory
piniheaven@fish:~$ ls /home
jack piniheaven
Linux Commands for Beginners lesson 6 -- usseradd,passwd commands
in this part, I will show you how to add user to your system and how to change user's password
1.COMMAND:
useradd
DESCRIPTION：
create a new user or update default new user information
SYNOPSIS:
useradd [options] LOGIN
OPTIONS:
-g, --gid GROUP
The group name or number of the user's initial login group.
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
A list of supplementary groups which the user is also a member of.
-m, --create-home
Create the user's home directory if it does not exist.
-s, --shell SHELL
The name of the user's login shell.
Example:
piniheaven@fish:~$ ls /home
piniheaven
piniheaven@fish:~$ sudo useradd jack -m -g users -s /bin/bash #create home folder for jack, add jack to users group and specify bash shell to jack
[sudo] password for piniheaven:
piniheaven@fish:~$ ls /home
jack piniheaven
2.COMMAND:
passwd
DESCRIPTION:
change user password
SYNOPSIS:
passwd [LOGIN]
Example:
piniheaven@fish:~$ sudo passwd jack
Enter new UNIX password:
Retype new UNIX password:
1.COMMAND:
useradd
DESCRIPTION：
create a new user or update default new user information
SYNOPSIS:
useradd [options] LOGIN
OPTIONS:
-g, --gid GROUP
The group name or number of the user's initial login group.
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
A list of supplementary groups which the user is also a member of.
-m, --create-home
Create the user's home directory if it does not exist.
-s, --shell SHELL
The name of the user's login shell.
Example:
piniheaven@fish:~$ ls /home
piniheaven
piniheaven@fish:~$ sudo useradd jack -m -g users -s /bin/bash #create home folder for jack, add jack to users group and specify bash shell to jack
[sudo] password for piniheaven:
piniheaven@fish:~$ ls /home
jack piniheaven
2.COMMAND:
passwd
DESCRIPTION:
change user password
SYNOPSIS:
passwd [LOGIN]
Example:
piniheaven@fish:~$ sudo passwd jack
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Linux Commands for Beginners lesson5 -- pidof,kill and ps commands
In this part,I will show you how to kill processes.
if you know your application's name,you can use pidof and kill commands to kill it.
DESCRIPTION:
finds the process id's (pids) of the named programs.
2.COMMAND:
kill
DESCRIPTION:
Terminate a Process
Example:
piniheaven@fish:~$ pidof firefox
8477
piniheaven@fish:~$ kill 8477
unfortunately,most of the time, we can not remenber what the application's name is exactily.In this case,you can use ps cammand to list processes.
SYNOPSIS
ps [options]
DESCRIPTION:
ps displays information about a selection of the active processes.
OPTION：
-a all w/ tty(TeleTYpe) except session leaders
-U by real user ID (supports names)
-u by effective user ID (supports names)
x processes w/o controlling ttys
example:
piniheaven@fish:~$ ps -ux #all of your Processes that are running
Warning: bad ps syntax, perhaps a bogus '-'? See http://procps.sf.net/faq.html
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
1000 1923 0.0 0.0 442624 3876 ? Sl 06:31 0:00 /usr/bin/gnome-keyring-daemon --daemonize --login
......
......
1000 26058 15.1 3.7 963772 224616 ? Sl 08:50 1:37 /usr/lib/firefox/firefox
1000 26416 9.9 2.0 687044 125308 ? Sl 08:50 1:02 /usr/lib/firefox/plugin-container /usr/lib/flashplugin-installer
1000 28660 0.0 0.0 22360 1276 pts/2 R+ 09:00 0:00 ps -ux
piniheaven@fish:~$ ps -aux #all uses's processes that are running
Warning: bad ps syntax, perhaps a bogus '-'? See http://procps.sf.net/faq.html
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 24592 2500 ? Ss 06:30 0:00 /sbin/init
......
......
root 25542 0.0 0.0 0 0 ? S 08:43 0:00 [kworker/0:3]
1000 26058 14.2 3.8 965884 232620 ? Sl 08:50 2:18 /usr/lib/firefox/firefox
1000 26416 9.0 2.0 687044 125308 ? Sl 08:50 1:10 /usr/lib/firefo
root 28661 0.1 0.0 0 0 ? S 09:02 0:00 [kworker/u:1]
1000 28670 0.0 0.0 22360 1272 pts/2 R+ 09:03 0:00 ps -aux
piniheaven@fish:~$ps-U piniheaven #the specified username's all process that are running
PID TTY TIME CMD
1923 ? 00:00:00 gnome-keyring-d
1934 ? 00:00:00 gnome-session
1969 ? 00:00:00 ssh-agent
......
......
21890 ? 00:00:45 gedit
23530 pts/2 00:00:00 bash
26058 ? 00:02:45 firefox
26416 ? 00:01:31 plugin-containe
28681 pts/2 00:00:00 ps
if you know your application's name,you can use pidof and kill commands to kill it.
1.COMMAND:
pidofDESCRIPTION:
finds the process id's (pids) of the named programs.
2.COMMAND:
kill
DESCRIPTION:
Terminate a Process
Example:
piniheaven@fish:~$ pidof firefox
8477
piniheaven@fish:~$ kill 8477
unfortunately,most of the time, we can not remenber what the application's name is exactily.In this case,you can use ps cammand to list processes.
3.COMMAND:
ps SYNOPSIS
ps [options]
DESCRIPTION:
ps displays information about a selection of the active processes.
OPTION：
-a all w/ tty(TeleTYpe) except session leaders
-U by real user ID (supports names)
-u by effective user ID (supports names)
x processes w/o controlling ttys
example:
piniheaven@fish:~$ ps -ux #all of your Processes that are running
Warning: bad ps syntax, perhaps a bogus '-'? See http://procps.sf.net/faq.html
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
1000 1923 0.0 0.0 442624 3876 ? Sl 06:31 0:00 /usr/bin/gnome-keyring-daemon --daemonize --login
......
......
1000 26058 15.1 3.7 963772 224616 ? Sl 08:50 1:37 /usr/lib/firefox/firefox
1000 26416 9.9 2.0 687044 125308 ? Sl 08:50 1:02 /usr/lib/firefox/plugin-container /usr/lib/flashplugin-installer
1000 28660 0.0 0.0 22360 1276 pts/2 R+ 09:00 0:00 ps -ux
piniheaven@fish:~$ ps -aux #all uses's processes that are running
Warning: bad ps syntax, perhaps a bogus '-'? See http://procps.sf.net/faq.html
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 24592 2500 ? Ss 06:30 0:00 /sbin/init
......
......
root 25542 0.0 0.0 0 0 ? S 08:43 0:00 [kworker/0:3]
1000 26058 14.2 3.8 965884 232620 ? Sl 08:50 2:18 /usr/lib/firefox/firefox
1000 26416 9.0 2.0 687044 125308 ? Sl 08:50 1:10 /usr/lib/firefo
root 28661 0.1 0.0 0 0 ? S 09:02 0:00 [kworker/u:1]
1000 28670 0.0 0.0 22360 1272 pts/2 R+ 09:03 0:00 ps -aux
piniheaven@fish:~$ps-U piniheaven #the specified username's all process that are running
PID TTY TIME CMD
1923 ? 00:00:00 gnome-keyring-d
1934 ? 00:00:00 gnome-session
1969 ? 00:00:00 ssh-agent
......
......
21890 ? 00:00:45 gedit
23530 pts/2 00:00:00 bash
26058 ? 00:02:45 firefox
26416 ? 00:01:31 plugin-containe
28681 pts/2 00:00:00 ps
Linux Commands for Beginners lesson 4 -- locate,updatedb,sudo,file commands
in this Part , I cover searching for files and directories with the locate, updatedb and sudo commands. I also cover examining file types with the file command.
1.command:
locate
description：
Search for entries in a mlocate database.
2.command:
updatedb
description：
Update a mlocate database.
3.command:
sudo
description:sudo allows a permitted user to execute a command as the superuser or another user,
as specified by the security policy.
option:
-s :
The -s (shell) option runs the shell specified by the SHELL
environment variable if it is set or the shell as specified
in the password database. If a command is specified, it is
passed to the shell for execution via the shell's -c
option.
4.command:
file
description:
determine file typeExample:
here,let's go to the Documents directory first,for I don't want to put my file system in chaos
piniheaven@fish:~$ cd Documents/
piniheaven@fish:~/Documents$ ls
assemble C++primer_ex C++primer_note Ebook linux QT_ex QT_note test
show what's in test directory
piniheaven@fish:~/Documents$ ls test/ #nothing is in test directory
let's create some files
piniheaven@fish:~/Documents$ touch test/jackFile.txt
piniheaven@fish:~/Documents$ touch test/tomFile.txt
if we can't remember where the jackFile.txt is,but we want to find out it.
piniheaven@fish:~/Documents$ locate jackFile.txt #Unfortunately,nothing was found
in that case,we need to update database
piniheaven@fish:~/Documents$ updatedb #pemission deny
updatedb: can not open a temporary file for `/var/lib/mlocate/mlocate.db'
so,we need to change user as root temporary
piniheaven@fish:~/Documents$ sudo updatedb
[sudo] password for piniheaven:
we can alse do it like this
(
piniheaven@fish:~/Documents$ sudo -s
[sudo] password for piniheaven:
root@fish:~/Documents# updatedb
root@fish:~/Documents# exit
exit
)
piniheaven@fish:~/Documents$locate jackFile.txt
/home/piniheaven/Documents/test/jackFile.txt #see,it works.
you can find out files,which even you can't remember what it is exactly name
piniheaven@fish:~/Documents$locate *File.tx*/home/piniheaven/Documents/test/jackFile.txt
/home/piniheaven/Documents/test/tomFile.txt
now,change to test directory
piniheaven@fish:~/Documents$cd test
piniheaven@fish:~/Documents/test$ ls
jackFile.txt tomFile.txt
there are two files in test directory,but we need more information about these files
piniheaven@fish:~/Documents/test$ filejackFile.txtjackFile.txt: empty #wow,it is empty
ok,let's write something into jackFile.txt
piniheaven@fish:~/Documents/test$ nano jackFile.txt
show what's in jackFile.txt
piniheaven@fish:~/Documents/test$ cat jackFile.txt
hello,I am jackFile
use file command again
piniheaven@fish:~/Documents/test$ filejackFile.txt
jackFile.txt: ASCII text
change to /bin directory
piniheaven@fish:~/Documents/test$ cd /bin
there are lots of executable commands in it
piniheaven@fish:/bin$ ls
bash dbus-uuidgen kbd_mode netcat plymouth-upstart-bridge true
bunzip2 dd kill netstat ps ulockmgr_server
busybox df less nisdomainname pwd umount
bzcat dir lessecho ntfs-3g rbash uname
bzcmp dmesg lessfile ntfs-3g.probe readlink uncompress
bzdiff dnsdomainname lesskey ntfs-3g.secaudit rm unicode_start
bzegrep domainname lesspipe ntfs-3g.usermap rmdir vdir
......
......
let's test what kind of file it is
piniheaven@fish:/bin$ file pwd
pwd: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0x5cff3ccc22aeea4fd1d161a76d054d98e333639f, stripped
piniheaven@fish:/bin$ filerm
rm: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0xc41b59f611884bf5e27498576915db6193387a52, stripped
Linux Commands for Beginners lesson3 -- introduce mv,cp,cat commands
1.command:cat
DESCRIPTION
concatenate files and print on the standard output
SYNOPSIS
cat [OPTION]... [FILE]...
Option:
-n, --number: number all output lines
Example:
piniheaven@fish:~/Documents/test$ ls
essay
piniheaven@fish:~/Documents/test$ cat essay #print essay 's content on the standard output
Hello.
Fine,thanks!
piniheaven@fish:~/Documents/test$ cat -n essay #print essay's content on the standard output and number all output lines
1Hello.
2Fine,thanks!
2.command:mv
mv - move (rename) files
SYNOPSIS:
mv [OPTION]... SOURCE... DIRECTORY
DESCRIPTION:
Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY.
Example:
piniheaven@fish:~/Documents/test$ ls
essay
piniheaven@fish:~/Documents/test$ mvessay essay.txt #rename essay as essay.txt
piniheaven@fish:~/Documents/test$ ls
essay.txt
piniheaven@fish:~/Documents/test$ mv essay.txt ../ #move essay.txt to previous directory
piniheaven@fish:~/Documents/test$ ls
piniheaven@fish:~/Documents/test$ cd ..
piniheaven@fish:~/Documents$ ls
assemble C++primer_ex C++primer_note Ebook essay.txt linux QT_ex QT_note test
3.command:cp
cp - copy files and directories
SYNOPSIS:
cp [OPTION]... SOURCE... DIRECTORY
DESCRIPTION:
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.
Example:
piniheaven@fish:~/Documents$ ls test/
piniheaven@fish:~/Documents$ cp essay.txt test/ #copy essay.txt to test directory
piniheaven@fish:~/Documents$ ls test/
essay.txt
DESCRIPTION
concatenate files and print on the standard output
SYNOPSIS
cat [OPTION]... [FILE]...
Option:
-n, --number: number all output lines
Example:
piniheaven@fish:~/Documents/test$ ls
essay
piniheaven@fish:~/Documents/test$ cat essay #print essay 's content on the standard output
Hello.
Fine,thanks!
piniheaven@fish:~/Documents/test$ cat -n essay #print essay's content on the standard output and number all output lines
1Hello.
2Fine,thanks!
2.command:mv
mv - move (rename) files
SYNOPSIS:
mv [OPTION]... SOURCE... DIRECTORY
DESCRIPTION:
Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY.
Example:
piniheaven@fish:~/Documents/test$ ls
essay
piniheaven@fish:~/Documents/test$ mvessay essay.txt #rename essay as essay.txt
piniheaven@fish:~/Documents/test$ ls
essay.txt
piniheaven@fish:~/Documents/test$ mv essay.txt ../ #move essay.txt to previous directory
piniheaven@fish:~/Documents/test$ ls
piniheaven@fish:~/Documents/test$ cd ..
piniheaven@fish:~/Documents$ ls
assemble C++primer_ex C++primer_note Ebook essay.txt linux QT_ex QT_note test
3.command:cp
cp - copy files and directories
SYNOPSIS:
cp [OPTION]... SOURCE... DIRECTORY
DESCRIPTION:
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.
Example:
piniheaven@fish:~/Documents$ ls test/
piniheaven@fish:~/Documents$ cp essay.txt test/ #copy essay.txt to test directory
piniheaven@fish:~/Documents$ ls test/
essay.txt
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