UNIX FOR SAP BASIS

CREATING AND DELETING FILES

•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 commands

•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