CREATING AND DELETING FILES
Shutdown
commands
•cat > filename
file
will be created
•cat
>> filename
append contents to existing file.
•touch
file1 file2
no.of files will be created.
•rm filename
file will be deleted.
CREATING AND REMOVING DIRECTORIES
•mkdir dir1 dir2
no.of directories will be created.
•rmdir dir1 dir2
no.of empty directories will be deleted
•rm –rf dir1
it removes directories with contents.
•cd
to change one directory to another
directory
•pwd
to know present working directory.
•ps –ef
to know all processes.
•kill pid
to kill particular process.
•kill –9 pid
to kill process forcefully.
•vi filename
to edit file in vi.
•ls filename
Lists all files and directories.
•ls –l
it
gives full information of files and directories.
•ls –a
it
displays hidden files
•ls –p
shows
difference b/w files and directories.
•ls –i
Displys inode no of files and directories.
File
permissions
We
have two ways to assign permissions to files
1. Numeric mode
2. Symbolic mode
Numeric mode
•We assign numerics to permissions like
read 4
write 2
execute
1
•chmod 777 filename/dirname
assign full permissions to all users.
•chmod 666 filename/dirname
it assigns read and write permissions
to all users
•chgrp newgroupname file/directory
it changes groupname for file or directory.
•chown newownername file/directory
it
changes owner for file or directory.
example; chown sidadm:sapsys newdir
Symbolic
mode
Here we assign symbols to users.
•
owner u
•
group g
•
others o
•
all a
•
read r
•
write w
•
execute x
•
adding permissions +
•
removing permissions -
To assign permissions
• chmod ugo+rwx file/dir.
example chmod 755 newdir
To remove permissions
• chmod ugo-rwx file/dir.
Network
communication
In hetrogenous and homogenous environment
•
telnet ipaddress
it connets to remote system
•
ftp ipaddress
• scp /dir ipaddress:/dir
it copies date from source system to
target system
• ssh ipaddress:mkdir /dir
it executes commands in remote
system.
Only in homogenous environment
• rlogin ipaddress
•
• rcp /dir ipaddress:/dir
•
• rsh ipaddress:rm /file
User commads
•useradd –u uid –g gid –G gid –d homedirecory –m –s sh username
it adds user g for primary group
G for secondary
group
d,m for homedirecoty
s for default shell
u user id
• su – username
to swith from one user to another user.
Users
monitoring
•who
displays all users who are currently
logged in system.
•who am I
displays detailed information about
current logged in user.
•last
displays information about when system
is lastly rebooted,who,time.
•finger
information about current logged in
user.
•df
it
displays all filesystems with sizes
•df –h
it
displays all filesystems with human readable form.
•shutdown
•init 0
like shutdown
•init 1
single user mode
•init 6
like
reboot
•reboot
•poweroff
To
copy a file
cp sourcefile targetfile
To copy empty directory
cp sourcedir targetdir
To copy directory with all contents
cp –r sourcedir targetdir
To
move file/ rename file
mv sourcefile targetfile
To
move directory rename directory
mv sourcdir targetdir
