perror Command in Linux
The perror command in Linux explains the error codes in MariaDB or MySQL environment. It is used to display human-readable messages corresponding to error codes. It is often used in debugging and development to understand the meaning of error codes.
Table of Contents
Here is a comprehensive guide to the options available with the perror command −
- Installation of perror Command
- Syntax of perror Command
- perror Command Options
- Examples of perror Command in Linux
Installation of perror Command
The perror command is a part of MariaDB. To install perror on Ubuntu, Kali Linux, Raspberry Pi OS, Debian, and other Debian-based distributions, use the command given below −
sudo apt install mariadb-client
To install it on Fedora, run the command given below −
sudo dnf install mariadb-client
To install it on Arch Linux, execute −
sudo pacman -S mariadb
To install perror on CentOS or RHEL, use the following command −
sudo yum install mariadb-client
Syntax of perror Command
The syntax of the perror command in Linux is as follows −
perror [options] [errorcode...]
In the above syntax, the [options] field is used to specify the optional flags to modify the behavior of the command. The [errorcode...] is used to mention one or more error codes to interpret. These can be either system error codes or MariaDB/MySQL-specific error codes.
perror Command Options
The options of the perror command are listed below −
| Flags | Option | Description |
|---|---|---|
| -I, -? | --help, --info | Display a help message and exit |
| -s | --silent | Display only the error message |
| -v | --verbose | Display the error code and message (This is the default behavior) |
| -V | --version | Display version information and exit |
Examples of perror Command in Linux
This section demonstrates the usage of the perror command in Linux with examples −
Checking System Error Codes
To decode the system error codes, use the perror command with the system error code numbers −
perror 2 13
The above command displays the description of the error type, which is OS error code and its description.
Here are some common system error codes −
| Error Codes | Description |
|---|---|
| 1 | Operation not permitted. |
| 22 | Invalid argument. |
| 17 | File already exists. |
| 28 | No space left on device. |
| 39 | Directory not empty. |
| 64 | Machine is not on the network. |
| 71 | Protocol error. |
| 111 | Connection refused. |
| 122 | Disk quota exceeded. |
| 126 | Command not executable. |
| 127 | Command not found. |
| 139 | Segmentation fault. |
Checking MariaDB/MySQL-Specific Error Codes
To get an explanation of MariaDB or MySQL-specific error codes, use the perror command with the code −
perror 1049
Other common MariaDB or MySQL-specific error codes are listed below −
| Error Codes | Description |
|---|---|
| 1045 | Access Denied: Incorrect username or password. |
| 1049 | Unknown Database: The specified database does not exist. |
| 1050 | Table already exists: Attempt to create a table that already exists. |
| 1064 | Syntax Error: A syntax error in the SQL statement. |
| 1062 | Duplicate entry: Attempt to insert a duplicate value into a unique key. |
| 1146 | Table does not exist: The specified table does not exist. |
| 1213 | Deadlock found: A deadlock error occurs when two or more transactions block each other. |
| 1205 | Lock wait timeout exceeded: A transaction waited too long for a lock. |
| 1061 | Duplicate key name: Attempt to create an index with a duplicate name. |
| 1030 | Got error from storage engine: An error occurred during data manipulation with the storage engine. |
| 1063 | Unknown column: Reference to a column that does not exist in the table. |
| 1136 | Column count does not match: The number of columns in the query does not match the table's structure. |
| 1156 | Column length exceeds limit: A column exceeds the maximum allowed length. |
| 1040 | Too many connections: The server has reached its maximum allowed number of simultaneous connections. |
| 1206 | Too long key prefix: The key length is too long for the specified table engine. |
| 1364 | Field does not have a default value: When inserting into a table, a field that does not allow NULL values is not given a value. |
| 1451 | Cannot delete or update a parent row: Occurs due to foreign key constraints when trying to delete a record that is referenced in another table. |
| 1452 | Cannot add or update a child row: Occurs due to foreign key constraints when trying to add or update a row that violates foreign key rules. |
Using Silent Mode
To suppress additional information from the output, use the -s or --silent option −
perror -s 17
Displaying Help
To display help about the perror command, use any option from -h, -help, --help, or -? −
perror -?
Conclusion
The perror command in Linux is a useful tool for interpreting error codes in MariaDB and MySQL environments. It helps display human-readable messages for system and database-specific error codes, helping in debugging and development. By using various options, such as silent mode or verbose mode, the output can be tailored to specific needs.