Commands: $ logname to check present working user. User2 $ clear
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| Directory permissions are:
Read: with this permission we can see the contents of the directory. Write: with this permission we can create or delete files in the directory. Execute: with this permission user can change into that directory. Without this permission user cannot change into that directory. Note: To modify a file you should have both read and write permissions. umask: Default file and directory permissions To assign all the permissions to a regular file the notation is 666. Since a regular file will not have executable permission. To assign all the permissions to a directory the notation is 777. Initial permissions of the files and directories depends upon current umask value (when a file is created newly the default permissions are given depending on umask value) To check the umask value, umask command is used. $ umask 0022 Here first zero is the sticky bit value; second zero for users; 2 for group; another 2 for others Umask value tells that not to grant specified permissions. For example as above umask value is 022 it means The default permissions of a file is 644 (666-022=644) and for directories 755 (777-022=755) After that permissions of files and directories can be changed by using chmod command. Filters UNIX/LINUX provides following filters Pipe, head, tail, tr, tee, grep commands Working with pipe: Pipe is used to communicate between two process called as “inter process communication”. $ cmd1 | cmd2 Output Screen Temp file T he result of cmd1 will be return to pipe temporary file. From this file cmd2 will read data and send to output screen. Note: multiple pipes can be used. Output Screen Download 122.5 Kb. Share with your friends:
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