Difference between revisions of "Linux/C2/File-Attributes/English-timed"
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| Syntax of the '''chmod''' command is | | Syntax of the '''chmod''' command is | ||
| − | <nowiki>chmod space [options] space mode space filename | + | <nowiki>chmod space [options] space mode space filename |
We may give the following options with '''chmod''' command. | We may give the following options with '''chmod''' command. | ||
Revision as of 11:11, 20 July 2015
| Time | Narration |
| 00:00 | Welcome to this spoken tutorial on Linux File Attributes. |
| 00:05 | The prerequisites 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. |
| 00:33 | File attribute is the characteristics that describes a file such as owner, file type, access permissions etc. |
| 00:45 | '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. |
| 01:00 | The syntax of chown command is chown space options space ownername space filename or directoryname |
| 01:13 | We may give 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. |
| 01:33 | -f : Prevents chown from displaying error messages. |
| 01:37 | Now we will look at some examples. |
| 01:40 | 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 file 'testchown' is shahid. |
| 02:18 | To change the owner of the file, type the command:
$ sudo space c-h own space that is a-n-u-s-h-a anusha space testchown that is t-e-s-t-c-h-o-w-n 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 -l and press Enter.
Here we can see the owner of the directory 'test_chown' is shahid. |
| 03:21 | 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 Ctrl+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 '''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 : Read w : Write x : Execute s : 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 others 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 '''Ctrl+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 <nowiki>=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: |
| 7:44 | $ 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. |
| 09:23 | 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 the 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 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 has been contributed by ----------------------(name of the translator) and this is -----------------------(name of the recorder) from --------------------------(name of the place)signing off . Thanks for joining. |
