Difference between revisions of "BOSS-Linux/C2/File-Attributes/English-timed"
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| To change the permission recursively and assign the '''read''' and '''execute''' access for everyone and also '''write''' access for the owner of the directory 'directory1', type the command: | | To change the permission recursively and assign the '''read''' and '''execute''' access for everyone and also '''write''' access for the owner of the directory 'directory1', type the command: | ||
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|'''chmod space minus capital R space 755 space directory1 '''press '''Enter'''. | |'''chmod space minus capital R space 755 space directory1 '''press '''Enter'''. | ||
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|12:41 | |12:41 | ||
| − | |'''Hard links''' are to associate multiple directory entries with a single '''inode.''' | + | |'''Hard links''' are to associate multiple directory entries with a single '''inode.''' '''ln''' is the command to make link. |
| − | '''ln''' is the command to make link. | + | |
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| 12:52 | | 12:52 | ||
Revision as of 11:58, 24 March 2017
| Time | Narration |
| 00:01 | Welcome to this spoken tutorial on Linux File Attributes. |
| 00:05 | The prerequisite for this tutorial is to create empty files named as example1, example2, example3, example4, example5 and testchown. |
| 00:18 | Please create empty directories named as test_chown and directory1 also. |
| 00:25 | A file attribute is metadata that describes or is associated with a computer file. |
| 00:34 | File attribute is the characteristics that describe a file, such as owner, file type, access permissions, etc. |
| 00:46 | c-h own command is used to change the ownership of the file or directory. This is an admin command, root user only can change the owner of a file or directory. |
| 01:01 | The syntax of the chown command is: chown space options space ownername space filename or directoryname. |
| 01:13 | We may give the following options with chown command. |
| 01:18 | -R : To change the permission on files that are in the sub-directories of the directory that you are currently in. |
| 01:28 | -c : Change the permission for each file. |
| 01:32 | -f : Prevents ch own from displaying error messages. |
| 01:37 | Now, we will look at some examples. |
| 01:41 | So, go to the terminal. We will move to the directory where we have created empty files and folders. For that, cd space Desktop slash file attribute and press Enter. |
| 01:56 | Now type the command: ls space -l space testchown that is t-e-s-t-c-h-o-w-n and press Enter. |
| 02:11 | Here we can see the owner of the testchown is "shahid". |
| 02:18 | To change the owner of the file, type the command sudo space c-h own space a-n-u-s-h-a anusha space testchown that is t-e-s-t-c-h-o-w-n and press Enter. |
| 02:36 | Enter the sudo password and press Enter again. Press Enter. |
| 02:44 | Now type: ls space -l space t-e-s-t-c-h-o-w-n and press Enter.
Here, we can see the new owner of the file is "anusha". |
| 03:03 | Now we will see how to change owner of the directory. |
| 03:07 | Type the command: ls space -l and press Enter. Here we can see the owner of the directory test_chown is "shahid". |
| 03:22 | To change the owner of the directory, type the command: |
| 03:26 | sudo space chown space minus capital R space a-n-u-s-h-a anusha space test_chown which is directory name and press Enter. |
| 03:44 | Enter the sudo password, if required, and press Enter again. |
| 03:49 | I will clear the screen by pressing Clt+L for our convenience. Now type: ls space -l and press Enter. Here we can see the new owner of the directory is "anusha". |
| 04:06 | chmod command is used to change the access mode or permissions of one or more files. |
| 04:13 | Syntax of the chmod command is: chmod space [options] space mode space filename
We may give the following options with the chmod command- |
| 04:29 | -c : Print information about files that are changed. |
| 04:34 | -f : Do not notify user of files that chmod cannot change. |
| 04:41 | There are following types of access or permissions- |
| 04:44 | r: that is Read
w: that is Write x: that is Execute s: that is Set user (or group) ID. |
| 04:54 | Alternatively, we may specify permissions by a three-digit octal-number. |
| 05:00 | The first digit stands for owner permission, the second stands for group permission and the third stands for other permission. |
| 05:09 | Permissions are calculated by adding the following octal values-
4: that is Read 2: that is Write 1: that is Execute. |
| 05:20 | Now we will look at some examples of chmod. Move to terminal and enter the command to add execute-by-user permission to file example1. |
| 05:30 | Before that I will again clear the screen by pressing Clt+l. |
| 05:36 | Now, let's type chmod space u+x space example1 press Enter. |
| 05:49 | Now, type: ls space -l space example1
press Enter to see the changes. |
| 06:01 | Here, you can see to assign the read/write/execute permission by owner, read/execute permission by group, and execute-only permission by others to file 'example1'. |
| 06:15 | Now type the command: chmod space 751 space example1 press Enter. |
| 06:26 | Now type: ls space -l space example1 and press Enter. |
| 06:35 | Here we can see that above command has assigned the read/write/execute permission by owner, read/execute permission by group and execute-only permission by others to file example1. |
| 06:52 | To assign read-only permission to file example1 for everyone, type the command: chmod space =r space example1 and press Enter. |
| 07:08 | Now type the command: ls space -l space example1 press Enter. |
| 07:19 | Here we can see that the read only permission has been assigned to file 'example1' for everyone. |
| 07:30 | To change the permission recursively and assign the read and execute access for everyone and also write access for the owner of the directory 'directory1', type the command: |
| 07:44 | chmod space minus capital R space 755 space directory1 press Enter. |
| 08:00 | Now type: ls space -l press Enter to see the changes. |
| 08:09 | To give the user execute permission on file 'example2', type the command:
chmod space u+x space example2 press Enter. |
| 08:27 | Now type the command: ls space -l space example2 and press Enter. |
| 08:40 | Here, we can see that execute permission has been assigned to user on 'example2'. |
| 08:50 | To add the write permissions to the group for file 'example3', type the command: chmod space g+w space example3. Press Enter. |
| 09:10 | And now, type: ls space -l space example3 press Enter. |
| 09:24 | Here we can see the write permission has been added to group. |
| 09:30 | To remove the write permissions for all, type the command: chmod space a-w space example3 press Enter. |
| 09:45 | Now type: ls space -l space example3 press Enter. |
| 09:55 | Here we can see the write permission for all has been removed. |
| 10:02 | chgrp command is used to change the group of one or more files to new group. |
| 10:10 | New group is either a group ID number or a group name located in /etc/group. |
| 10:20 | Only the owner of a file or a privileged user may change the group. |
| 10:26 | The syntax for the chgrp command is: chgrp space [options] space newgroup space files. |
| 10:36 | Let's go to terminal. Now we will look at some examples of chgrp command.
Type the command ls space -l space example4 press Enter. |
| 10:57 | Here we can see the group permission is for user "shahid". |
| 11:03 | To change the group permission, type the command: sudo space chgrp space rohit space example4. |
| 11:20 | Press Enter. Enter the 'sudo' password if required. |
| 11:27 | Now type the command: ls space -l space example4 . Press Enter. |
| 11:38 | Here we can see that the group has changed from "shahid" to "rohit". |
| 11:46 | The inode-number is a unique integer assigned to a device. |
| 11:51 | Inode stores basic information about a regular file or a directory. |
| 11:57 | All the files are hard-links to inodes. |
| 12:00 | Whenever a program refers to a file by name, the system actually uses the filename to search for the corresponding inode. |
| 12:12 | We can use ls space -i command to see the inode-number of a file. |
| 12:19 | Type the command: ls space -i space example5 press Enter. |
| 12:29 | Number written before the file is the inode-number of the file. |
| 12:35 | Inodes are associated with precisely one directory at a time. |
| 12:41 | Hard links are to associate multiple directory entries with a single inode. ln is the command to make link. |
| 12:52 | The syntax of ln command to create the hard link is: |
| 12:57 | ln space source space link where source is an existing file and link is the file to create. |
| 13:06 | Now we will look at some examples of hard-links. |
| 13:10 | Let me clear the screen again. Now type the command: ln space example1 space exampleln press Enter. |
| 13:25 | To display the inode number of both the files, type the command:
ls space -i space example1 space exampleln press Enter. |
| 13:41 | Here we can see that inode number of both the files are same; file 'exampleln' is the hard-link for file 'example1'. |
| 13:54 | Soft-link i.e. symbolic link is a special type of file that contains a reference to another file or directory in the form of an absolute or relative path. |
| 14:07 | The syntax of ln command to create soft links is: |
| 14:12 | ln space -s space {target-filename} space {symbolic-filename}. |
| 14:19 | Now we will look at some examples of soft-link. |
| 14:25 | To create the soft-link, type the command: ln space -s space example1 space examplesoft . |
| 14:40 | Press Enter. |
| 14:43 | Now, to display the inode number and list of both the files, type the command:
ls space -li space example1 space examplesoft. |
| 15:01 | Press Enter. |
| 15:03 | Here we can see that inode number of both the files are different and 'examplesoft' is a soft-link of 'example1'. |
| 15:16 | So, in this tutorial we have learnt about the Linux Files Attributes like changing permission, ownership and group of a file. |
| 15:26 | We also learnt about the inode, soft and hard-links of a file. |
| 15:31 | This brings me to the end of this tutorial. |
| 15:35 | Spoken Tutorials are a part of the "Talk to a Teacher" project, supported by the National Mission on Education through ICT. |
| 15:44 | More information on the same is available at the following link. |
| 15:50 | This script is contributed by Anusha Ambala and Shahid. Thanks or joining. |
