Transcript Proposal Student Competition Enhancement

Module 3 Manipulating Files
and Directories
The cp command
• Used to copy files and Directories
• To copy a single file:
# cp file.txt /tmp
• To copy and rename a file:
# cp file.txt /tmp/new-file.txt
• To copy a directory (Recursively)
# cp -r /tmp /home/avi
Cutting, Pasting and Renaming
with mv
• The mv command can be used for both cut-paste and
for renaming purposes.
• Renaming:
# mv file.txt new-file.txt (in the same directory)
• Cut and Paste:
# mv /tmp /home/avi
• Cut, paste and rename:
# mv /tmp /home/avi/old-tmp
• Please remember that when using the mv command
with directories we do not use the -r option.
Deleting files and directories
with rm
• To delete a single file:
# rm file.txt
• To delete a directory:
# rm -r /home/avi/Downloads
• Deleting with interaction question:
# rm -ir /home/avi/Downloads
• Ignoring Interaction:
# rm -rf /home/avi/Downloads
Creating new directories with
mkdir
• To create a new directory:
# mkdir ort-dir
• To create a new directory path:
# mkdir -p /home/avi/ort/public/documents
• What will happen here ?
# mkdir -p ~/ort{1,2,3,4}/linux{a,b,c,d}/doc{1,2,3,4}
Creating a new empty file and an
instant file
• Use the touch and tee command to create a new
empty file:
# touch ~/new-file.txt
• The touch command can also be used to change a
file time stamp
• Use the tee command to simultaneously write to
screen and to a file:
# tee ort.txt
Hello Class
Use ^D to end writing to file and return to shell
Looking inside a file
• As Linux is a TUI based OS we need the ability to
look inside files without editing them:
• The cat command display the file on the screen
(standard output)
# cat /etc/passwd
• the more and less commands:
# more /etc/httpd/conf/httpd.conf
# less /etc/httpd/conf/httpd.conf
Looking at top and bottom of a file
• Use the head command to look at the top of a file:
# head -3 /etc/passwd
• Use tail command to look at the bottom of a file:
# tail -8 /etc/passwd
• Use the tail command to get a “live” look at a file:
# tail -f /var/log/messages
The wc command
• Displays line, word, or character count of a file
• Command format: wc [ -lwc ] filename(s)
• Use the following options:
-l
Count lines
-w Count words
-c Count bytes
• Examples:
# wc /etc/passwd
39
264
1421 caesar.txt
# wc –l /etc/passwd
39 caesar.txt
Linux Wildcards
• Without these cool little things called shell wildcards,
working on the Linux command line is pretty painful.
Wildcard
Matches
*
zero or more characters
?
exactly one character
[abcde]
exactly one character listed
[a-e]
exactly one character in the given range
[!abcde]
any character that is not listed
[!a-e]
any character that is not in the given range
{yes,no}
exactly one entire word in the options given
Wildcard examples
• the following removes every file from the current
directory:
# rm *
• The following command moves all the HTML files,
that have the word "linux" in their names,from the
working directory into a directory named dir1:
# mv *linux*.html dir1
Wildcard examples
The following displays all files that begin with d
and end with .txt:
# less d*.txt
The following command removes all files whose names
begin with junk., followed by exactly three characters:
# rm junk.???
Wildcard examples
With this command you list all files or directories
whose names begin with ort, followed by exactly one
numeral:
# ls ort[0-9]
This lists all files or directories beginning with ort,
followed by exactly two numerals:
# ls ort[0-9][0-9]
Wildcard examples
The following lists all files or directories whose name
starts with either ort or linux,
followed by any single character between a and c:
$ ls {ort,linux}[a-c]
This command copies all files, that begin with an
uppercase letter, to directory dir2:
$ cp [A-Z]* dir2
This deletes all files that don't end with c, e, h or g:
$ rm *[!cehg]
Symbolic links
• Symbolic links (soft) are used for
two main reasons:
• To link a file or directory across file systems.
• Backwards compatibility – when a command name,
or file name changes, symbolic links are often used to refer
to new files by both old and new names.
• Symbolic links, unlike hard links, can cross
file system boundaries, and can link directories.
• To create symbolic links use the command:
# ln –s filename linkname
Hard Links
• A hard link is merely an additional name for an
existing file on Linux or other Unix-like operating
systems.
• Hard links cannot link directories.
• Cannot cross file system boundaries.
Use the ln command:
# ln file-name hard-link-name
• Watch the inode number with:
# ls -i
Exercise
1.
2.
3.
4.
5.
6.
7.
Copy the etc directory to your home folder.
Create a shortcut from the tmp directory to your home folder.
In your copy of etc directory create a hard link to passwd
Rename the etc directory (in your home folder) to my_etc
How many lines are in ~/my_etc/httpd/conf/httpd.conf
Create a new directory with your name in your home folder
Create a new file under the directory with your name and in that file
write down your name and family name
8. Create a new directory path under your home folder containing 5
different directories
9. Create a hard link from /tmp to your home directory. Is it possible ?
10. how can you find your PATH environment variable ?
11. how can you change your PATH environment variable ?
Exercise
1. Find all files and directories under my_etc ending
with a dot (.) and one character.
2. Try the following commands under my_etc:
# more [A-Z]* my_etc
# ls –ld my_etc/[!a-m]*
# file /usr/bin/*x*
(use exact path)
# ls –ld /my_etc/[a-z]*[0-9]
# ls -a my_etc/.[!.]*
The VI editor
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Introduction to vi
The vi command
vi modes
Command Mode
Insert Mode
Execution Mode
Last Line Mode
Introduction to VI
• vi is an interactive editor that is used to create and/or
change text files.
• vi is a standard Unix editor and is cross platform.
• Alternatives include emacs, pico, nano, xedit, gedit
• vi is old in concepts, and hard to master, but once
mastered it is a very powerful and fast editing tool
• In some systems, especially for administrators, vi is
the only option
• The Linux version vim acts very similar to windows’
notepad, and is hence preferred in Linux
The VI Command
• Start vi:
$ vi filename(s)
For full editing functionality
$ view filename(s) To open file(s) in read-only mode
$ vi –r filename
To recover a crashed file
• vi will occupy the entire terminal screen. You will now be interacting with
vi until you exit and return to the shell prompt
• vi comes from old times, its commands actually belong to its
predecessor ed, which was working on printer terminals, its mode of
operation was:
• Display a line
• Run commands to change things in the line
• Go to another line
VI Modes
• Three modes in VI:
1.Command Mode
2.Insert Mode
3.Execution Mode
VI Command Mode
• When we open VI for editing we find ourselves in
command-mode.
• The keyboard acts differently but we can type-in
commnds
• To return to the command mode all we need to do is
press ESC
• If you are lost always press ESC to return to
command-mode
VI Command Mode
• In order to make sure that you are in command mode
press ESC.
• Basic command format:
count command scope
10dw
The Above command will delete 10 next words from the
cursor location
VI Command Mode
• x delete character under cursor
• X delete character to left of the cursor
• The d command deletes to buffer (like cut in word).
• dd
Deletes complete line
• dw
Deletes to the start of the next word
• d3l
Deletes the next three characters
• d0
Deletes to the beginning of the line
• d$
Deletes to the end of the line
• d1G
Deletes to the beginning of the file
• dG
Deletes to the end of the file
• D
Deletes to the end of the line
VI command Mode
• Cut, Copy and Paste Commands
• yy Yank a complete line
• 20yy Yank 20 complete lines
• dd
cut a line
• 5dd cut 5 lines
• P paste above you
• p paste under you
VI command Mode
•u
• G
• 1G
• 212G
•J
•.
undo
go to end of file
go to first line
go to line 212
Join current and next line
Repeat last command
VI Insert mode
• In this mode the VI starts acting like a regular
notepad.
• To leave the insert mode press ESC (back to
command mode)
• To jump from command to insert mode you can:
# press the Insert button
And.. A , a , I , i , O , o
Search and Replace
• Search Only:
• /pattern
Search forward for patterns
• ?pattern Search backwards for pattern
•n
Repeat last search
•N
Repeat last search in the opposite direction
Search and Replace (in execution :)
•:1,$s/old/new/g
Replaces all old
with new all over the file
•:1,20s/old/new/gc Replaces all old
with new between lines 1-20 and asks for
confirmation before changing.
•:n,ms/old/new/g
replaces all old
with new between lines n-m
Execution Mode :
• :r file
• :w
• :w!
• :w file
• :wq
• :x
• :q
• :q!
• :!cmd
• :r!cmd
the file
Read file and place its contents after the line
Write – save changes
Write file overriding protection mode
Write to named file
Write and quit
Write and quit (exit)
Quit
Force quit without saving changes
Execute shell command
Execute shell command and insert the output to
VI options
• vi has many options to control behavior.
• To list available options and their status, type:
:set all
• To enable an options (for example line numbering), type:
:set number
- Will show line numbers
:set showmode – Will show when we are in INSERT mode
• To disable an option (for example line numbering), type:
:set nonumber
:set noshowmode
• In vim there are many more commands. One very recommended is:
:syntax on - Which will use colors to make the edited file more
readable, according to its type - Useful for editing C files and bash
scripts for example (requires syntax files to be installed )
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