Linux permissions are a set of rules that determine the level of access or control on user , file or directory. It helps to protect the system and its data by ensuring that only authorized users access.
To change file permission in Linux chmod command is used.
chmod command is categorized into three categories:
- user
- group
- other
Command can be specified in either of two ways:
- relative permission
- absolute permission
1)relative permission: In relative permission it changes the permission specified in command and leave other permission unchanged.
syntax: chmod categorization permission filename
example chmod u+r file.txt
Following operation specified that need to performed:
+ assign permission
– remove permission
= assign absolute permission for all
permission specified r, w ,x(read, write, execute)
2)Absolute permission: permission specified by setting all nine permission bits explicitly.in the chmod we used three octal number.
Example Of Absolute And Relative Permission In Linux
Here is the practical example of absolute and relative permission that make you fully understand about different permission in Linux/Unix
1.Assign execute permission to the user but other permission remain unchanged for the file marks.dat
2.Assign execute permission to all the category for the file stud list.txt and mark.dat.
3.Assign read permission to the categories group and other ,revoke execute permission from other for files marks.dat
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