Commands used in Linux

Basic Linux Commands
• File Handling
• Text Processing
• System Administration
• Process Management
• Archival
• Network
• File Systems
• Advanced Commands


Primary – man(manual) pages.
man <command>  ­ shows all information about the
command
<command> ­­help  ­ shows the available options
for that command   
Secondary – Books and Internet
File Handling commands
• mkdir – make directories                                                                
         Usage: mkdir [OPTION] DIRECTORY...                              
        eg. mkdir prabhat
• ls – list directory contents                                                                
        Usage: ls [OPTION]... [FILE]...                                              
        eg. ls, ls ­l, ls prabhat
• cd – changes directories                                                                   
        Usage: cd [DIRECTORY]                                                       
File Handling(contd...)
• pwd ­  print name of current working directory                             
      Usage: pwd                       
• vim – Vi Improved, a programmers text editor                              
      Usage: vim [OPTION] [file]...                                                  
      eg. vim file1.txt
                                          
File Handling(contd...)

cp – copy files and directories                                             
         Usage: cp [OPTION]... SOURCE DEST                    
         eg. cp sample.txt sample_copy.txt                             
               cp sample_copy.txt target_dir                             

mv – move (rename) files                                                    
        Usage: mv [OPTION]... SOURCE DEST                    
        eg. mv source.txt target_dir                                        

File Handling(contd...)
• rm ­ remove files or directories                                     
         Usage: rm [OPTION]... FILE...                              
         eg. rm file1.txt , rm ­rf some_dir   
• find – search for files in a directory hierarchy                
        Usage: find [OPTION] [path] [pattern]                   
        eg. find file1.txt, find ­name file1.txt
• history – prints recently used commands                        
         Usage: history           
Pattern
A Pattern is an expression that describes a set of
strings which is used to give a concise description
of a set, without having to list all elements.
eg. ab*cd matches anything that starts with ab and
ends with cd etc.
ls *.txt – prints all text files
Text Processing
• cat – concatenate files and print on the standard output                  
     Usage: cat [OPTION] [FILE]...                                                  
     eg. cat file1.txt file2.txt
         cat ­n file1.txt                                                                         
• echo – display a line of text                                                             
     Usage: echo [OPTION] [string] ...                                              
     eg. echo I love India                                                                   
Text Processing(contd...)
• grep ­ print lines matching a pattern                                                
    Usage: grep [OPTION] PATTERN [FILE]...                              
    eg. grep ­i apple sample.txt                                                          
                                                                  
• wc ­ print the number of newlines, words, and bytes in files          
     Usage: wc [OPTION]... [FILE]...                                               
     eg.  wc file1.txt                                                                           
Text Processing(contd...)
• sort – sort lines of text files                                                   
     Usage: sort [OPTION]... [FILE]...                                    
     eg. sort file1.txt 
         sort ­r file1.txt
Linux File Permissions
• 3 types of file permissions – read, write, execute
• 10 bit format from 'ls ­l' command
                 1             2 3 4      5 6 7     8 9 10
             file type    owner     group    others
eg. drwxrw­r­­   means owner has all three permissions,
      group has read and write, others have only read            
  permission
• read permission – 4, write – 2, execute ­1   
        eg. rwxrw­r­­   = 764
              673    =   rw­rwx­wx
System Administration
• chmod – change file access permissions                                         
       Usage: chmod [OPTION] [MODE] [FILE]                              
      eg. chmod 744 calculate.sh                                                        
• chown – change file owner and group                                             
      Usage: chown [OPTION]... OWNER[:[GROUP]] FILE...       
System Administration (contd...)
•  su –  change user ID or become super­user                     
       Usage: su [OPTION] [LOGIN]                                        
       eg. su remo, su
• passwd – update  a user’s authentication tokens(s)          
       Usage: passwd [OPTION]                                              
       eg. passwd
• who – show who is logged on                                            
       Usage: who [OPTION]                                                   
       eg. who , who ­b , who ­q
Process Management
• ps – report a snapshot of the current processes                               
     Usage: ps [OPTION]                                                                   
     eg. ps,  ps ­el       
• kill – to kill a process(using signal mechanism)                              
     Usage: kill [OPTION] pid                                                          
Archival
• tar – to archive a file                                                                      
      Usage: tar [OPTION] DEST SOURCE                                   
      eg. tar ­cvf /home/archive.tar /home/original                           
            tar ­xvf /home/archive.tar
• zip – package and compress (archive) files                                   
      Usage: zip [OPTION] DEST SOURSE                                   
      eg. zip original.zip original
• unzip – list, test and extract compressed files in a ZIP archive    
Network
• ssh – SSH client (remote login program)                                   
    “ssh is a program for logging into a remote machine and for        
   executing commands on a remote machine”     
 Usage: ssh [options] [user]@hostname 
 eg. ssh ­X guest@10.105.11.20                                  
• scp – secure copy (remote file copy program)                           
          “scp copies files between hosts on a network”        
Usage: scp [options] [[user]@host1:file1] [[user]@host2:file2]
 eg. scp file1.txt guest@10.105.11.20:~/Desktop/
File Systems
• fdisk – partition manipulator                                                 
     eg. sudo fdisk ­l
• mount – mount a file system                                                 
    Usage: mount ­t type device dir                                         
    eg. mount /dev/sda5 /media/target                                     
• umount – unmount file systems                                            
    Usage: umount [OPTIONS] dir | device...                         
    eg.  umount /media/target                                                  
         
File Systems(contd...)
• du – estimate file space usage                                                        
     Usage:  du [OPTION]... [FILE]...                                              
     eg. du    
• df – report filesystem disk space usage                                          
    Usage: df [OPTION]... [FILE]...                                                
    eg. df   
• quota – display disk usage and limits                                            
    Usage: quota [OPTION]                                                            
Advanced Commands
• reboot – reboot the system                                                    
       Usage: reboot [OPTION]                                                
     eg. reboot                                                                         
               
• poweroff – power off the system                                          
       Usage: poweroff [OPTION]
     eg. poweroff

Editor commands
• kate – KDE Advanced Text Editor                                                
      Usage:  kate [options][file(s)]                                                   
      eg. kate file1.txt file2.txt                                                           

• vim – Vi Improved, a programmers text editor                              
      Usage: vim [OPTION] [file]...                                                  
      eg. vi hello.c
• gedit ­ A text Editor. Used to create and edit files.                        
               Usage: gedit [OPTION] [FILE]...                                    
Process Management(contd...)
• bg – make a foreground process to run in background             
         Usage: type 'ctrl+z'  and then 'bg <job id>' 
• fg – to make background process as foreground process          
          Usage: fg [jobid]
• jobs – displays the names and ids of background jobs             
          Usage: jobs
Advanced Commands (contd...)
• sed ­  stream editor for filtering and transforming text         
    Usage: sed [OPTION] [input­file]...                                  
    eg. sed 's/love/hate/g' loveletter.txt                                    
             
• awk ­ pattern scanning and processing language                  
    eg.  awk ­F: '{ print $1 }' sample_awk.txt
• find ­ search for files in a directory hierarchy                 
                    Usage: find [OPTION] [path] [pattern]       
                                    eg. find ­name file1.txt
• locate – find or locate a file
     Usage: locate [OPTION]... FILE...
     eg. locate file1.txt

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