Transcript In the last Session… ls -l command seven fields nine permissions of a file ls -ld file ownership file permissions (three-tiered file protection system) changing file permissions -

In the last Session…
ls -l command
seven fields
nine permissions of a file
ls -ld
file ownership
file permissions (three-tiered file protection
system)
changing file permissions - chmod
relative permissions
• Changing file permissions – chmod
– Absolute permissions
– The security implications
– Using chmod recursively (-R)
• Directory permissions
• Changing file ownership
– chown
– chgrp
THE vi EDITOR
CONTENTS
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The vi basics
Input mode – entering and replacing text
Saving text and quitting – the ex mode
Navigation
Editing text
vi basics
• To write and edit some programs and scripts, we
require editors
• UNIX provides vi editor for BSD system –
created by Bill Joy
• Bram Moolenaar improved vi editor and called it
as vim (vi improved) on Linux OS
vi <filename>
Command mode
non existant lines
Input mode
enter, edit text
Current cursor position
Current line
• ctrl-w to delete any wrong word
• esc to return to command mode
• Beep indicates a key pressed
unnecessarily
• Ex mode – execute mode – last line mode
• :x saves file on disk and shifts the control
from editor to prompt mode ($)
• Command mode
copy and delete text, can’t enter or replace
text
• Input mode
every key pressed is a text
• ex mode
save and perform substitution by pressing
: and get back to default command mode
THE REPEAT FACTOR
• vi provides repeat factor in command and
input mode commands
• Command mode command k moves the
cursor one line up
• 10k moves cursor 10 lines up
• Undo whenever you make a mistake
esc u
• Clearing the screen in command mode
ctrl-l
• Don’t use (capslock)
vi commands are case-sensitive
• Avoid using the PC navigation keys
INPUT MODE
:set showmode
messages like INSERT MODE, REPLACE
MODE, CHANGE MODE, etc will appear in the
last line
Pressing ‘i’ changes the mode from command to
input
To append text to the right of the cursor position,
we use a, text
I and A behave same as i and a, but at line
extremes
I inserts text at beginning of line
A appends text at end of line
Opening a new line
o opens a new line below the current line
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r<letter> replacing a single character
s<text/word> replacing text with s
R<text/word> replacing text with R
Press esc key to switch to command mode after
you have keyed in text
INPUT MODE COMMANDS
COMMAND
i
a
I
A
o
O
r
s
S
FUNCTION
inserts text
appends text
inserts at beginneing of line
appends text at end of line
opens line below
opens line above
replaces a single character
replaces with a text
replaces entire line
SAVING TEXT AND QUITTING
:W
saves file and remains in editing mode
:x
saves and quits editing mode
:wq saves and quits editing mode
:w <filename>
save as
:w! <filename>
save as, but overwrites existing file
:q
quits editing mode
:q!
quits editing mode by rejecting changes made
:sh
escapes to UNIX shell
:recover
recovers file from a crash
• THANK YOU