Linux Error Codes

Linux error codes are those codes that are displayed if an error occurs in the system while working or using a program. The errors can be recognized with the help of error codes. The error codes assist us in recognizing the source of error.

If we are working on a Linux system, it is obvious that we may encounter errors. Some errors can be minor and may not lead to interruption of the program. But there can be some errors that can cause a system or program to stop responding. These errors can lead to loss of data or may prevent the program from completing. Mostly errors are displayed in the form of codes or messages.

In this section, we will see errors in C programming and a list of possible errors in the Linux system.

Linux Errors in C programming

A skilled programmer should know how to deal with the errors. C programming language does not provide direct support for error handling. We have to detect the source of the error and deal with it. In C language, the return values display the failure or success. If a function in the C program fails, we must handle the error accordingly; otherwise it records the errors last in a log file.

While executing the C programs, we might notice some error numbers such as "Error no is: 17". Here, the error no 17 means the file already exists. Every error number has some meaning.

The C language supports a variable 'errorno.' By using this error number variable, we can use some error handling functions to handle it properly.

To use the external variable error number, we have to include a header file 'errno.h.' The <error.h> header file is used to define the 'errno' variable. The errno variable is set by the system calls and library functions in the error occurrence. There are two important functions in the C programming language to deal with errors; perror and strerror. The perror function is used to print the error description and the sterror function returns a string having error code.

Let's display the list of error codes by using errno.

Linux errno

The errno utility is used to looks up errno codes, macro names, and the corresponding descriptions. For example, if we provide ENOENT on a Linux system, it will display the code 2 and description " No such file or directory." If we provide the code 2, then it will display the ENOENT and its description.

If errno utility is not installed on our machine, it will display the error as follows:

To install it, execute the below command:

By executing the above command, the moreutils package is installed on our machine that contains the errno utility.

Display the List of Error codes

To display the list of the error codes, execute the command as follows:

The above command will display the list of error codes by RedHat. Consider the below output:

Display the information of an error number

To display the information of a particular error number, execute the command as follows:

The above command will display the description of error number 2. Consider the below output:

Display the information of an error name

To display the information of a particular error name, execute the errno command, followed by the error name. For example, to display the information of an error name 'ESRCH,' execute the command as follows:

The above command will display the information about the specified error name. Consider the below output:

Display the error using strings

To display an error description by using a string from the description, execute the command as follows:

The above command will display the errors whose description contains string permission. Consider the below output:

List of Linux system Errors

Following is a partial list of possible errors of Linux system: