Linux – File Commands (Faq)
1. Learn the below commands
ls -lrt -> usee this regularly
ls -al -> to view the hidden files
2. To navigate to your linux home directory
cd
cd ~
cd $HOME
cd – –> go backs to the directory where you come from.
cd.. –> Navigate to previous directory.
3. What are the options used for cat command.
[sdbt ~]$cat > file1.txt #To create a new filelinux is open source
linux is written by Linux Torvalds
linux is simple and elegant
written in the c programming language
cntrl+z [sdbt ~]$ cat file1.txt #To view the file contents
linux is open source
linux is written by Linus Torvalds
linux is simple and elegant
written in the c programming language
[sdbt ~]$ cat >> file1.txt #To append the exist file
Linux is user for servers
linux is fast and secure
Its acts has multi user platforms
[sdbt ~]$ cat file1.txt #To view the file contents
linux is open source
linux is written by Linus Torvalds
linux simple and elegant
written in the c programming language
Linux is user for servers
linux is fast and secure
Its acts has multi user platforms
[sdbt ~]$ cat file1.txt > file2.txt #To divert output in another file
4. How to create a empty file
touch filename
> filename
5. Vi Editors
vi is a text editor. It can be used to edit all kinds of plain text. It is especially useful for editing programs.
There are three mode
– Command mode
– Insert mode
– Escape mode
Command mode
1G – Move Cursor into First Line of the File
nG – Move Cursor into nth Number of the Line in File
G – Move Cursor into Last Line of the Line in File.
yy – Copy a Single line.
nyy – Copy Multiple line.
dd – Delete a Single Line.
ndd – Delete Multiple Line.
dw – Delete Single word.
x – Delete a Single character.
r – Replace a Single Character.
R – Replace a Multiple Character.
p – Paste the deleted or copied information.
u – Undo the changes
k – Move the cursor upward.
j – Move the cursor downward.
h – Move the cursor left side.
l – Move the cursor right side.
Insert mode
i – allow insert cursor location.
I – allow insert start line of cursor location.
a – allow insert next to cursor location.
A – allow insert end line of cursor locaion.
o – open a new line below and allow insert from the cursor location.
O – open a new line above and allow insert from the cursor location.
Escaple mode
Esc + :
w -Save
q -Quit
! -Force
n -next
/string -Search string in file
rew -review the multiple file once more
7. Directory creation and removal
[sdbt ~]$ mkdir dir1 # create directory[sdbt ~]$ mkdir dir2 dir3 dir4 # create Multiple Directory
[sdbt ~]$ mkdir -p dir5/sdira/sdirb/sdirc # create a Parental with Subdirectory
[sdbt ~]$ rmdir dir1 # removes empty directory
[sdbt ~]$ rm file.txt # removes/deletes a file
[sdbt ~]$ rm -rf dir5 # removes the directory which have contents
8. head and tail commands
head
Give Output the first 10 lines of the file
[sdbt ~]$ head alphabets.txtaA
bB
cB
dD
eE
fF
gG
hH
iI
jJ [sdbt ~]$ head -3 alphabets.txt
aA
bB
cB
tail
Give Output the bottom 10 lines of the file
rR
sS
tT
uU
vV
wW
xX
yY
zZ [sdbt ~]$ tail -3 alphabets.txt
xX
yY
zZ
10. Other mandatory commands
sort
sort lines of text files.
animals
animals
fruits
fruits
vechicles
vegetables
wechicles
uniq
Filter adjacent matching lines.
animals
fruits
vechicles
vegetables
wechicles
comm
Compare sorted files file1 and file2 line by line
animals
animals
birds
fruits
fruits
vechicles
vegetables
wechicles
diff
Compare files line by line
2d1
< animals 4d2 < animals 6a5 > birds
wc
Print line,word and byte counts for each fie
26 26 78 alphabets.txt [sdbt ~]$ wc -l alphabets.txt
26 alphabets.txt
-l lines
-w words
-c bytes
cp
Copy files and directories
mv
Rename sorce to destination, or Move sources to directory.
11. What is the use of strings commands.
strings is used for filter characters from the binary file.
We use this command to create pfile from spfile , when spfile is corrupted.