errstr Command in Linux

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Linux, the powerhouse of many modern-day operating systems, is known for its robustness and flexibility, especially when it comes to handling errors. One of the lesser-known yet useful commands in the Linux arsenal is the errstr command. This command is part of a suite of tools that come in handy for system administrators and developers alike.

Table of Contents

Here's a professional guide to using the errstr command with different options in Linux −

• Understanding errstr Command
• How to Use errstr Command in Linux?
• Example of errstr Command in Linux

Understanding errstr Command

The errstr command is linked to the ckstr utility, which prompts a user and validates the response. It is particularly useful in scripting and programming within the Linux environment, where error handling and user prompts are common.

The errstr command and its associated options provide a robust framework for handling user input and errors within scripts and programs. It's a testament to the flexibility of Linux and its ability to cater to a wide range of scenarios in system administration and development.

How to Use errstr Command in Linux?

The errstr command in Linux is a utility that comes with OpenSSL and is used to display the meaning of error codes, typically in hexadecimal format. This command can be particularly useful when you encounter an error code while working with OpenSSL and need to understand what the error message means.

Syntax of errstr Command in Linux

The basic syntax of the errstr command is as follows −

openssl errstr error_code

Where error_code is the hexadecimal error code you wish to look up.

Here's a breakdown of the options available with the errstr command −

For those interested in diving deeper into the errstr command and its usage, the UNIX and Linux Forums provide a comprehensive man page that can be accessed for more detailed information.

Example of errstr Command in Linux

The errstr command is a simple yet powerful tool for deciphering OpenSSL error codes. While it doesn't have many options, its utility lies in its ability to translate obscure hexadecimal codes into meaningful messages that can assist in troubleshooting.

Here's a detailed look at how to use the errstr command with examples −

Decoding a Simple Error Code

If you encounter an error code like 2006D080, you can use the errstr command to find out what it means −

openssl errstr 2006D080

This indicates that the error is related to the BIO routines, specifically BIO_new_file and that the issue is the absence of a file.

If you encounter an error code like 2006D080, you can use the errstr command to find out what it means −

openssl errstr 2006D080

This will return a human-readable error message, such as −

error:2006D080:BIO routines:BIO_new_file:no such file

Error Code with Multiple Components

Error codes can sometimes be more complex, including multiple components separated by colons. For example −

27594:error:2006D080:lib(32):func(109):reason(128):bss_file.c:107:

To decode this, you would use the errstr command with the hexadecimal part of the code −

openssl errstr 2006D080

And receive a similar error message explaining the components of the error.

Understanding the Output

The output from the errstr command provides a breakdown of the error code −

• error − This prefix indicates that it's an error message.
• 2006D080 − The hexadecimal error code.
• BIO routines − The library or module where the error occurred.
• BIO_new_file − The function within the module that caused the error.
• no such file − The reason for the error.

Scripting Example

Here's an example of how you might use errstr in a bash script to check for errors after running an OpenSSL command −

#!/bin/bash

# Run some OpenSSL command
output=$(openssl some_command 2>&1)

# Check if the command failed
if [ $? -ne 0 ]; then
# Extract the error code
error_code=$(echo $output | grep -oP 'error:\K([0-9A-F]{8})')

# Lookup the error message
error_msg=$(openssl errstr $error_code)

# Log or handle the error
echo "Error encountered: $error_msg"

However, you can use it in scripts or combine it with other commands to automate error handling or logging −

Note − The errstr command does not have a wide range of options, as its primary purpose is to translate error codes into readable messages.

Conclusion

The errstr command is a valuable tool for troubleshooting when working with OpenSSL or other applications that may provide opaque error codes. By understanding how to use this command, system administrators and developers can quickly identify the source and reason for errors, streamlining the debugging process.