FUNDAMENTALS OF LINUX PRESENTED BY: Md. Kalimullah ID-VGT138T MCA 1
SOME BASIC COMMANDS ls - directory or dir* ls –l - Directory listing with long filenames, owner, and permissions ls –a – show the hidden file ls –ll -show the directory files w –save exit q –without save exit wq –save and exit wq! –forcefully exit. ls –ld - Show only the directories matching the search ls – r - Show subdirectories also ( just like dir /s ) ls –sharl – sort by size, all files, including hidden ls –lart – sort by date, reverse order (newest @ the bottom of list) -s - sorts by size, largest first -r - reverses any sort command, i.e. ls –rS sorts smallest first -t - sorts by modification time, recent first -u - sort by last accessed time -x - sort by file extension
Linux Commands #pwd -print working directory will show you the full path to the directory you are currently in. # shred - overwrite a file to hide its contents The result is that your file is so thoroughly deleted it is very unlikely to ever be retrieved again. # ln s - test symlink Creates a symbolic link named symlink that points to the file test # free -Displays the amount of used and free system memory.
Linux Commands w – show who is logged on and what they are doing usage: w who –show who is logged in usage: who who b> - last system boot time whoami – prints the effective user id. whereis ls -Locates binaries and manual pages for the ls command. cat – displays the contents of the file on the screen.
Linux file system First let see file structure in Linux :- 1) Standard directory structure / - the topmost ( / means where the file system is stored like C: in windows ) /dev - all the devices are accessible as files /var - “variable” data such as mails, log files, databases /usr - almost all the packages installed /etc - configuration files /home - home directories for all the users /root - home directory of the privileged user root /mnt - used to mount other directories/partitions.
Linux file system # rm it is used to delete files & # rm -r it is use to delete directorys recursively usage : $ rm -r /root/folder # mkdir it is used to create directory (folder) usage : $ mkdir /etc/folder # touch it is used to create files usage : $ touch /root/temp
PERMISSION• u - User who owns the file. g - Group that owns the file. o - Other. a - All. r - Read the file. w - Write or edit the file. x - Execute or run the file as a program.• Read –r-4 Permission –read- (rwx)=7• Write –w-2 Permission – write- (r-x)=5• Execute-x-1 Permission-execute-(-wx)=3
PERMISSION Permissions:chmod 777 file.htm CHMOD can also to attributed by using Numeric Permissions: 400 read by owner 040 read by group 004 read by anybody (other) 200 write by owner 020 write by group 002 write by anybody 100 execute by owner 010 execute by group 001 execute by anybody Examples The above numeric permissions can be added to set a certain permission, for example, a common HTML file on a Unix or Linux server accessible over the Internet would be given the below permissions.
PERMISSIONS• chmod 644 file.htm• This gives the file read/write by the owner and only read by everyone else (-rw-r-- r--).• Files such as scripts that need to be executed need more permissions. Below is another example of a common permission given to scripts.• chmod 755 file.cgi• This would be the following 400+040+004+200+100+010+001 = 755 where you are giving all the rights except the capability for anyone to write to the file.cgi file(- rwxr-xr-x).• chmod 666 file.txt• Finally, another common CHMOD permission is 666, as shown below, which is read and write by everyone.• Tip: The above commands are all done through the command line. However, if you upload a file using FTP these permissions can also be adjusted through many FTP clients by right-clicking the file and choosing permissions.
HOW CAN CHANGE THE TEMPORARY “HOSTNAME” SETTING #hostname #hostname station.example.com #hostname //check it #station //setting temporary hostnameHOW CAN CHANGE THE PERMANENT “HOSTNAME” SETTING # vi / etc/sysconfig/network/ #HOSTNAME=station.example.com #service-config-network #service network restart #clear
THIS IS NEW COMMANDS IF YOU WANT SEE THE CURRENT DATE #date +”%D%H:%M:%S” IF YOU WANT TO PRINT ANY MESSAGE #echo “WELCOME TO VOLKSGEIST TECHNOLOGIESE” BASIC COMMAND #/ dev /fdo //flopy drive (A) #/dev /fd1 //flopy drive (B) #/dev /had //master drive on primary #/dev /hda1 //1-partition #/dev /hda3 //save drive #/dev /hdc //master drive secondry #/dev /hdl //save drive secondry
PERMISSION DISTRIBUTE SIZE The 100 are for the OWNER of the file 400 –read 200 –write 100 –execute There are for Groups of the file 40 –read 20 –write 10 –execute There are for every one else 3 –read 2 –write 1 -execute
CREATE MACHINE FOR COMMUNICATE CLIENT CLIENT SERVER SERVER#hostname server.example.com #hostname client.example.comIp address-172.24.16.2 Ip address-172.24.16.3RAM-1024 RAM-512HDD-80GB HDD-80GBPing-127.24.16.3 Ping-127.24.16.2