Permissions in Linux

Create three users: Example: [root@test119 ~]# useradd kavita [root@test119 ~]# useradd ramu [root@test119 ~]# useradd srinu Make ramu the member of the group kavita Example: [root@test119 ~]# gpasswd -a ramu kavita Adding user ramu to group kavita Create a directory Example: [root@test119 ~]# mkdir /linux Check the default permission of the above created directory [root@test119 ~]# ls -ld /linux/ drwxr-xr-x 2 root root 4096 Aug 28 11:26 /linux/ Give full permissions to the above created directory Example using absolute mode [root@test119 ~]# chmod 777 /linux/                          (or) Example using symbolic mode [root@test119 ~]# chmod ugo=rwx /linux/ Check...

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Group Membership in Linux

Syntax:-  [root@localhost~]# gpasswd <option> <arguments> <groupname> Options: -M -- Add multiple users to a group -A -- Add a group Administrator -a -- Add a single user to a group -d -- Delete a user from a group Example:- Add multiple users (ravi, sunil) to the group marketing Note: Before doing this the group marketing should be exists. [root@test119 ~]# gpasswd -M ravi,sunil marketing To check if the users are added to the group [root@test119 ~]# grep marketing /etc/group marketing:x:2006:ravi,sunil Example:- Add user rani as the administrator for the group marketing [root@test119 ~]# useradd rani [root@test119 ~]# gpasswd -A rani marketing To check if rani has been added as the administrator for the group marketing [root@test119 ~]# grep marketing...

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Group Administration in Linux

Creating a Group Syntax:-  [root@localhost~]# groupadd <groupname>                           (or) [root@localhost~]# groupadd <option> <argument> <groupname> Options: -g -- Group ID -0 -- Override Example:- Creating a group Sales with default options [root@test119 ~]# groupadd sales To check if the group has been created [root@test119 ~]# tail -5 /etc/group avdefs:x:504: ali:x:2001: tom:x:2002: anu:x:2003: sales:x:2004: Example:- Creating a group mktg whose group id (GID) is 750 [root@test119 ~]# groupadd -g 750 mktg To check if the group has been created [root@test119 ~]# tail -5 /etc/group ali:x:2001: tom:x:2002: anu:x:2003: sales:x:2004: mktg:x:750: Modifying...

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Creating an User

Syntax :- [roort@localhost~]# useradd <username> or [roort@localhost~]# useradd <option> <argument> <username> Options: -u -- UID                                                        -c -- comment -g -- Primary Group Name or GID                  -d -- Home directory -o -- Override                                                ...

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Basic Commands - 2.1

To View the calender Example : To see the current month [root@localhost ~] # cal      August 2011   Su Mo Tu We Th Fr Sa     1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Example : -   TO see the past, current and next month [root@localhost ~] # cal -3        July 2011            August 2011         September 2011  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa                 1  2      1 ...

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Basic Commands - 2.0

Copying files and Directories [root@localhost ~]# cp <option> <source> <destination> Example :- To copy a file [root@localhost ~]# cp completereport /opt To check if the file has been copied [root@localhost ~]# cd /opt [root@localhost ~]# ls completereport Example :- To copy a directory [root@localhost ~]# cp -r directory1/ /opt/ To check if the directory has been copied [root@localhost ~]# cd /opt [root@localhost ~]# ls completereport directory1 Moving files and directories Syntax :- [root@localhost ~]# mv <option> <source> <destination> Example :- To Move a file [root@localhost ~]# salesreport /opt To check if the file has been moved completereport directory1 salesreport Example :- To move a directory [root@localhost ~]# mv...

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Creating Directories & Directory Navigation

Syntax :- [root@localhost~]# mkdir <option> <directory name> Example :- Creating a single directory [root@localhost~]# mkdir directory1 Example :- Creating multiple directories [root@localhost~]# mkdir direcoty2 directory3 directory4 To check if the directories have been created [root@localhost~]# ls -d directory* directory1  directory2  directory3  directory4 Example :- To create nested directories (Sub directories inside directories) [root@localhost~]# mkdir -p d1/d2/d3/d4 To check if the nested directories have been created [root@localhost~]# ls -R d1 /d1: d2 /d1/d2: d3 /d1/d2/d3: d4 /d1/d2/d3/d4: Note :- To list the contents and create a file or directory in a location different from the present working directory, Specify the complete path (example...

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Basic Commands -1.2

Creating files and adding data using cat command Syntax :- [root@localhost~]# cat <option> <arguments> Example :- To create a file along with some data [root@localhost~]# cat > salesreport This file contains the sales report for the month Aug. ( Now press Ctrl+d to Save ) Example :- To create one more  file along with some data [root@localhost~]# cat > mktgreport This file contains the mktg report for the month of Aug. ( Now press Ctrl+d to Save ) Example :- To read the contents of a file [root@localhost~]# cat salesreport This file contains the sales report for the month of Aug. Example : - To append (add) to a file [root@localhost~]# cat >> mktgreport This year the efforts in mktg have increased. Ctrl+D Check the contents of the file mktgreport [root@localhost~]#...

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Basic Commands -1.1

To check the Present working directory Syntax :- [root@localhost`]# pwd Example :- [root@localhost~]# pwd /root To See the contents of a directory (folder) Syntax :- [root@localhost~]# ls <option> <argument> Options: -l          Long list including attributes  -a         All files and directories including hidden -d         To check for a particular file or directory -R        Recursively, to see the contents in a tree structure Example :- To list the contents of the present working Directory [root@localhost~]# ls  anaconda-ks.cfg    install.log.syslog  POOL.logpid Desktop         ...

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