Read-only filesystem linux. Fixing Ubuntu Filesystem Errors "The file system is read-only

Although it surpasses Windows in some parameters, it can also spoil the mood of the user by giving errors. One of these is the inaccessibility of the file system. And this applies to both ordinary flash drives and hard drives in some situations. You can solve the problem. However, even experienced users do not always know how to fix the error when Ubuntu says: "The file system is read-only." We tried to give the answer in this article.

An index area is made up of inodes that have the same structure. The size of the field depends on the number of inodes it contains. This number is determined when the file system is created and cannot be changed. The inodes contain information about the file. Each inode can describe at most one file.

The index descriptors contain the following information about the file. Address information - 40 bytes. ... The first 10 addresses are direct addresses of the first 10 data blocks of the file. If the file is more than 10 blocks, indirect blocks are used. Indirect blocks are located in the data field, but contain block numbers, not file data. The eleventh address contains the dummy block number, which contains the numbers of the next data blocks in the file. This is called one indirect addressing. The twelfth block contains the indirect block number, which contains the number of indirect blocks that already contain blocks of data blocks.

There can be several reasons for file access problems in Ubuntu.

First of all, it is worth checking whether this file system is definitely working. In the case of a flash card, this is easy to do. Try to open it from a Windows computer. Another system can quickly troubleshoot the drive. The same goes for memory cards, Chinese players and other cheap storage media. Often times it may be about them.

Automatic installation of partitions

Disables executable executables on the file system. Another security option. Unconditionally unmounting the file system can cause system failure or data corruption in the file system. Then run the command to mount the partition in the existing directory.

To unmount the disk, run the command. The file system is a mechanism for organizing various types of storage and presenting them to the user. Each file system consists of several elements. The launcher contains the information the system needs to access the file system. A data block is an area for our data. The file system can be mounted or unmounted. Displays the amount of free and used space on the file system.

This is called double indirection. Through the thirteenth block, triple indirect addressing is implemented. The list of free blocks is provided through a linked list. Directories are represented as files, in which a two-line structure is recorded for each file contained in the directory: an inode and a file name.

The boot block takes up one block and contains the program that starts the boot of the operating system. The rest of the blocks are grouped into groups with the same size. Each group contains a portion of the file system and a copy of the global system systems critical to system integrity — the superblock and group descriptors.

In the case when the hard disk is problematic, it will be much more difficult to perform the check. If your computer has two systems, check if your HDD is working properly on Windows. These methods will allow you to determine the source of the malfunction.

Formatting

In many cases, simple formatting of the file system helps to restore functionality. It is especially easy to do this on a USB flash drive. True, we are not always ready to part with the information that is already on it. Transfer all data to a computer running Windows and format the problem drive.

We can specify the device name or its mount point as the target. Mount options mount. In previous chapters, we often had different reads of data on the hard drive. It's time to collect information about them and organize them. The first thing to keep in mind is performance. All links to the filesystem are quite slow and often even represent a speed bottleneck in our code. Therefore, you should try to do the best you can and cache the results of some of them so that subsequent code can refer to them.

Group descriptors are written in each group in a row of numbers one after the other. Each inode contains information about which blocks belong to the file. This is achieved by using pointers pointing to blocks in the group data field. Returns - with a success number greater than or equal to zero representing the file descriptor from the system tables.

Opens a file; if the file does not exist, it first creates it using the third argument. Positioning of the primitive in the file. On success, a new file descriptor is returned. Creating a hierarchical file system organization - creating and destroying a directory, creating and destroying links, changing the current directory. Destruction of the directory; the directory should not contain any files.

With a disc, it is unlikely that someone will raise a hand to do this. Formatting can destroy a lot of important information. Moreover, if the Ubuntu file system is damaged, the problem must be looked for elsewhere.

Every access to a file must begin by opening it. Then, in a loop, we load a one kilobyte file. Thus, data can be processed "in parallel" with reading. Once completed, your connection to the file should be closed. From the above code, we can cast a loop and load everything in one go.

Note the quality of the examples provided. Rename the files we link to some non-existent ones. The first will send us a wave of warnings within 30 seconds, the second will make them “only” a few. Therefore, we must prepare everything so that we can control the messages ourselves. Time to create primitive error handling. It should provide us with a link to the file, that is, the value of the resource.

Changes the current process directory; the old current directory of the process is issued and the inode of the new directory is loaded. All directories on the road must exist and the process has execute rights for them. In the case of a hard link, the file is also guaranteed, and the original name is destroyed, but the symbolic link is not. In fact, it doesn't even check for the existence of the original file when creating the symbolic link. A symbolic link is interpreted when trying to access a file through it. In addition, a symbolic link can be created across filesystem boundaries to a regular file, special file, and directory.

Checking for errors

You can check the disk for errors not only on Windows. Ubuntu also has ample arsenal for this. This can be done both with the help of commands and using a special application. First, let's take a look at the method using standard tools.

We look at the list of drives:

We check a specific drive:

The specified file name is excluded from the file system; the number of hard link fields in the file inode is reduced by 1; if this number becomes 0, the file is destroyed. Changes file permissions The process executing this primitive must be the administrator or the owner of the file.

This manual is intended for advanced users. You must obtain administrator rights to connect other devices. Let's list all available disks and partitions. The result will look like this. It can be any empty directory, even in your home directory.

hdparm -i / dev / sdf | grep Model

In the example sdf is taken, but your disk name may differ.

If the volume was mounted, then before checking, this action must be canceled:

Now we check the volume for bad blocks - problem areas:

badblocks -s / dev / sdf1> / root / badblock

The progress will be displayed as a percentage.

Is this only an active ringtone?

You can find a complete list on the man page using.

Is only the file loaded

Did you save that time, money? Did he help solve the problem? Are you ready to provide a symbolic award for further development? There are over 000 lines, tips and tricks, including many different templates.

Hard drives and other storage spaces are attached under the letters, for example, this is nothing special, although the fact that individual drives do not have a common top point is strange to me. In fact, the desktop is nothing more than a folder located on the system drive somewhere in the user's folder. There are several hidden system files elsewhere for more confusion. You have a "shortcut" is a file type of a symbolic link, you have a directory is a file type of a directory, a process is a file type of a process.

Now we mark the bad blocks so that the system stops using them:

e2fsck -l / root / badblock / dev / sdf1

In theory, this should help you fix problems with any kind of media. If scanning disks for errors did not help, then it's time to use a convenient utility - GParted.

Gparted

On this system, to read a 3.5-inch floppy disk, it must be installed first. Before you start editing, he will give you the knowledge you need. You don't have to list all the devices you own. Rulers starting with # are comments.

Comments usually include information about the file, or thus denote lines that are temporarily excluded from the file operation. In the third, we have headers that define what the following information is. File System — Indicates the device or file system to be installed and the location in which it is located.

First, you need to install this program. This can be easily done using the command:
sudo apt-get install gparted
Open GParted. All carriers will be displayed in front of us. Among them there should be a problematic inaccessible one - if the utility sees errors, it will mark it with an exclamation mark.
Now open our disk and click on the "Section" button located at the top.
In the drop-down menu, select "Check for errors". The program will scan the disk and, possibly, find problems, after which the file system will become available not only for reading.

Access rights

Finally, the last reason why we lose access to data management on media is violated rights. It can also be encountered by experienced users using root mode. When we use various commands, not fully understanding their essence, or run programs with extended privileges, the system can block access by mistake.

Mount point is where the device should be installed. We will refer to this location when using the device. Each operating system has its own file system, which it prefers and in which it runs. Dump - The specified value indicates that the file system should be unmounted. The default is 0, which means you don't need to unmount the filesystem.

A value of 1 means that you need to check the section first. On the contrary, a value of 2 means that the disk or partition should be checked next. Examples of titles have been mentioned. They can have different names, but the order of the values must be the same!

Then we see a message from Ubuntu: "The file system is read-only." Special teams will help to remove such a problem.

The following command is suitable as a generic method:

Instead, you must enter the username. The chown command is responsible for changing the folder permissions. The -R attribute means that this section is read-only by the user. Sudo will undo these changes. In the example, the problem was in the home partition, if you have problems with the flash drive, then you should enter its directory.

Before installing any device, you need to know how it is identified in the system. Knowing where a particular hard drive is located, we can find its partitions. Also note that there can be up to four basic and extended partitions. The program will display about the partitions on this drive.

After reading the above text, you can now mount partitions and devices. To mount a device you can use the command. You can expand on this. This mount makes sense for media other than hard drives. If the system does not detect the device after installation, it must be installed by the device. Programmers had to write "again", and the driver in the first versions caused errors that could lead to data loss.

The Ubuntu file system works slightly differently than on Windows. Therefore, any disks under its control behave differently. Because of this, new errors arise that cannot be encountered on Windows.

This command will mount the filesystem read-only. Then, preferably at the end, add a ruler. You must write this on one line. These parameters are no longer described - you read them at the beginning of this article. Also keep in mind that mount locations must exist!

There are several reasons why it is useful to keep some directories on separate filesystems. The directory where the file system should be installed. In its simplest form, it is used as follows. # Mount device of the mount point.

We now know how to fix the problem with disk editing problems. The matter can be both in the malfunction of the devices, and in the incorrect definition of rights. The main thing is to correctly identify the problem and fix it. Fortunately, this is not the most serious of all errors, although it can cause trouble for the user.

There can be several reasons for file access problems in Ubuntu.

Formatting

Checking for errors

We look at the list of drives:

We check a specific drive:

hdparm -i / dev / sdf | grep Model

In the example sdf is taken, but your disk name may differ.

If the volume was mounted, then before checking, this action must be canceled:

Now we check the volume for bad blocks - problem areas:

badblocks -s / dev / sdf1> / root / badblock

The progress will be displayed as a percentage.

Now we mark the bad blocks so that the system stops using them:

e2fsck -l / root / badblock / dev / sdf1

In theory, this should help you fix problems with any kind of media. If scanning disks for errors did not help, then it's time to use a convenient utility - GParted.

Gparted

First, you need to install this program. This can be easily done using the command:
sudo apt-get install gparted
Open GParted. All carriers will be displayed in front of us. Among them there should be a problematic inaccessible one - if the utility sees errors, it will mark it with an exclamation mark.
Now open our disk and click on the "Section" button located at the top.
In the drop-down menu, select "Check for errors". The program will scan the disk and, possibly, find problems, after which the file system will become available not only for reading.

Access rights

Then we see a message from Ubuntu: "The file system is read-only." Special teams will help to remove such a problem.

The following command is suitable as a generic method:

sudo chown -R: / home /

The Ubuntu file system works slightly differently than on Windows. Therefore, any disks under its control behave differently. Because of this, new errors arise that cannot be encountered on Windows.

How to enable writing to read-only folders in Total Commander for Android. We wrote about a wonderful program, the file manager for Android Total Commander, which can easily replace all other Android programs of this kind (ASTRO, Root Explorer, ES Explorer).

Total Commander is Russified, has root support, the ability to connect plugins, two-panel mode, and is absolutely free for life. That is completely, advertising is also absent.

However, upon closer acquaintance with the program, it turned out that mounting system partitions for writing in Total Commander just won't work. In the Root Explorer program, for example, this can be done by clicking on the " Mount rw"There is no such button or similar menu item in Total Commander.

However, as it turned out, there is a way out of this situation thanks to the wide possibilities for customizing the program. And today we will tell you how to add the button we need to the program buttons panel within one minute.

Instructions:

1. Start Total Commander and, if necessary, open the button bar by clicking on:

2. You can add a button to the panel by clicking on:

3. In the window that opens, select "Function type:"

4. Select "Internal Command"

5. In the "Command" field, select "119 Remount"

6. Click on OK / Apply

So when you want to put everything together, you have to write. Explode. Under no circumstances do you read files this way. The meaning of such a code can be summed up in a simple comparison: the package is only for immediate decompression. It serves no purpose and it takes up the necessary time.

Mention should also be made of the termination of the so-called "According to you from computer science". The solution is best illustrated with an example. However, the disadvantage of such a solution is that, having written the code, we can bury ourselves in blocks if we have lost the main thread of the program, and we cannot think of all possible situations that may occur.

There can be several reasons for file access problems in Ubuntu.

This operation is performed by a public function. It is essentially a string of bits in which each bit or group of bits has a specific meaning. After using the file, it must be closed using a function. Reading data from an open file is done using the function.

If it is exactly at the end of the file, the function returns zero, and on error, it returns. The operations of writing and reading in and out of a file are performed at a specific position in the file, considered the current position. For example, each read operation updates the current position indicator, increasing its number of bytes read.

Data records look similar to reading. Miscellaneous is just the destination of the data. It returns the number of bytes in the file, and we can use this to monitor if the add operation actually succeeded. The function takes two parameters: a filename and a text to write, and firm does not mangle binary data.

Let's ask ourselves what if we need to add additional content. This script will now add data to the file rather than overwrite it. In many cases, it is useful to know what we have in our catalogs. We can obtain it using a family of functions that provide us with a variety of information about files. They all assume that the filename is.

Formatting

On error, the function returns. Any use of a system function is very important to validate its return value. Search for file attributes. A pointer indicating the area of memory in which the state function returns this information must be specified as the second parameter of the function. The memory area must be reserved in advance in order to preserve the state structure.

Appendix: Other functions for working with directories and files

Directories are essentially files with a special format. Checking files in a directory looks like this. Each call to these functions returns a pointer to a heavy structure that will find information about reading the reading directory. Directory entries will be transferred one by one until the last entry is reached. As shown above, the only information that can be extracted from the direct structure is the name of the directory entry. This is true both for modified user data, that is, for his work and for system data.

When using them, we must keep performance in mind. Reading all the data on disk is slow, so try to compress as much as possible from one function call. Therefore, we have to write a mechanism to check if the compilation can be started or if it is not needed. Everything seems to look right - the script reports all the questions correctly. But it does it too slowly because we have overloaded it with a lot of links to the hard drive. If you run it on a high traffic site, it will be worse than other scripts.

It's even recommended, especially if you plan on replacing your computer from time to time. Thus, the data used cannot be changed. This does not mean that it is enabled, but the system recognizes and can use save if the environment is configured to do so. The choice of the mode is made in the first seconds after the start, you have the choice to start in the permanent or fake mode.

Continuous mode is when you want to disable saving data. By default, this utility works in a simplified way called a "helper". "Expert" mode is detailed below and is not intended for those users who are less well suited to computers. Assistant mode begins by detecting external and internal drives. If one or more external drives are detected, the utility offers to activate saving to this drive, or you will select the required external drive from the list. A negative answer will force the proposal to use that internal drive.

Let's try to change it a little. Instead of performing hundreds of new functions each time, we use as much of the data we already have. This is the correct philosophy for working with files. We've devoted a very large chapter to files. A much more powerful and powerful tool is the database. This issue is discussed in the next section of this book. But should the files be thrown away anyway? Contrary to the indications, reading records from a database is generally slower than a file, and for rudimentary application settings that do not require complex sorting and extensive relationships, it may be tempting to replace them with files.

Checking for errors

We look at the list of drives:

We check a specific drive:

Typically, from the user's point of view, file systems are organized around the ideas of files and directories. Files are objects that encapsulate information of a particular type, as well as directory group files and other directories within them. Any file or directory can be identified by its name, which is absolutely specified as a pathname or relative to the current directory.

For fixed and floppy disks, information is stored using their magnetic properties. A hard disk contains multiple storage folders inside, and a floppy disk is made up of one floppy disk. The face of the disc is divided into tracks, which are concentric circles in which information can be stored. Tracks are divided into sectors, a sector that conveys a fixed amount of information. Reading and writing information on the disk is performed at the data block level. A block can consist of one or more sectors.

hdparm -i / dev / sdf | grep Model

In the example sdf is taken, but your disk name may differ.

If the volume was mounted, then before checking, this action must be canceled:

Now we check the volume for bad blocks - problem areas:

badblocks -s / dev / sdf1> / root / badblock

The progress will be displayed as a percentage.

A hard disk can be partitioned by the user, with each partition behaving like a separate disk at the user level. A partition stores a file system, which means that multiple file systems can be found on a single physical disk. For ordinary personal computers, partition information is stored at the beginning of the disk in the so-called partition table. It contains 4 records that memorize positions, sizes and types of disk partitions. The stored memory partitions at the beginning of the disk are called primary partitions, which can obviously contain up to four.

Now we mark the bad blocks so that the system stops using them:

e2fsck -l / root / badblock / dev / sdf1

In theory, this should help you fix problems with any kind of media. If scanning disks for errors did not help, then it's time to use a convenient utility - GParted.

Gparted

However, it is possible that a new partition table is created within any main partition, referencing partitions that are physically within the current partition and are called extended partitions. The first sector of a partition or disk that contains the system is called the boot sector. It contains the following information.

Directories are stored as special structures, such as tables, in which each record represents a file. In fact, the directory is saved as a regular file, but contains information about other files. There is a root directory stored in the file allocation table that has a limited size.

First, you need to install this program. This can be easily done using the command:
sudo apt-get install gparted
Open GParted. All carriers will be displayed in front of us. Among them there should be a problematic inaccessible one - if the utility sees errors, it will mark it with an exclamation mark.
Now open our disk and click on the "Section" button located at the top.
In the drop-down menu, select "Check for errors". The program will scan the disk and, possibly, find problems, after which the file system will become available not only for reading.

Access rights

Directory entry structure. File distribution table. It is essentially a picture-like structure that stores within its linked lists that indicate the clusters that make up the files. The number of the first cluster of the file is stored, as already noted, in the directory corresponding to this file.

Example. The pointer node area is a fixed size when the filesystem is created and contains an entry for each file that can be created in this support. The paging area is reserved for storing images of a process when it is temporarily removed from memory to make room for other processes. However, as a rule, separate partitions are used for the paging area. Inode structure An inode contains important information about its associated file. Rights are of three types and are grouped into three categories: user rights to a user group - user rights in the group of owners of others - rights of all other users.

The last area contains the blocks in which the files are stored.
The file name number of the index node associated with the file.
Each file has only one inode.
You can see more directory entries pointing to the same index node.
Specifies the owner of the file identifier of the file group of file permissions.

Such a link is viewed by the user as a file with its own name, but in fact refers to another file on disk.

Then we see a message from Ubuntu: "The file system is read-only." Special teams will help to remove such a problem.

The following command is suitable as a generic method:

Any operation performed on the referenced file will have an actual effect on the referenced file. If deletion is required, the effect depends on the type of link. Links are of two types. Physical symbolism. ... Symbolic links are actually individual files, marked with a special code that contains the full name of the specified file. Removing them does not affect the file. They can refer to directories as well as files and folders from another partition or another drive, but they have the disadvantage that a separate index node must be created for them and, in addition, take up disk space through their contents.

The Ubuntu file system works slightly differently than on Windows. Therefore, any disks under its control behave differently. Because of this, new errors arise that cannot be encountered on Windows.

You can create links to files or folders with the B command. Special files that indicate drives or partitions are used in an operation called mounting a file system. This means that after installation, the entire directory and file structure of the file system will be located in this directory.

The mechanism is especially effective because it offers the ability to have a unitary directory structure that group files from multiple partitions or drives. The data without any parameters reflects the file systems that are currently installed on the system.