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Linux / UNIX: Encrypt Backup Tape Using Tar & OpenSSL
To encrypt a backup tape using tar and OpenSSL in Linux/UNIX, you can follow these steps:rn rn Create a backup archive using tar command. For example, to create a backup of /home directory, run: rn rn rn rn tar czvf /dev/st0 /homern rn rnThis will create a compressed backup of the /home directory an
Bash Shell: Trim Leading White Space From Input Variables
In Bash, you can use parameter expansion to trim leading white space from input variables. Here's an example:rn rn rn #!/bin/bash input= " hello world" rntrimmed= ${input#"${input%% ]*}"} rn echo "Original input: " $input "" rn echo "Trimmed input: " $trimmed "" rn rn rnIn this example, the inpu
mod_setenv: Lighttpd Send Custom Headers
In Lighttpd, you can use the mod_setenv module to send custom headers to the client. Here's how you can do it:rn rn Enable the mod_setenv module: If the mod_setenv module is not already enabled, you'll need to enable it in your Lighttpd configuration file. Add the following line to the file:rn rn rn
HowTo: Upgrade Red Hat Enterprise Linux to v5.5
Upgrading Red Hat Enterprise Linux (RHEL) to version 5.5 involves a few steps. Here is a general procedure to upgrade RHEL to version 5.5:rn rn Backup your system: Before you upgrade your system, make sure you have a backup of your system in case anything goes wrong. rn Update your current version:
How To Save A File In Vim / Vi Without Root Permission With sudo
When you're editing a file in Vim/Vi and you need to save the changes to the file, but you don't have the necessary permissions, you can use the :w !sudo tee % command to save the file with root permission. Here are the steps:rn rn Open the file with Vim/Vi: Open the file you want to edit with th
nginx: Setup SSL Reverse Proxy (Load Balanced SSL Proxy)
To set up a reverse proxy with SSL (Secure Sockets Layer) on Nginx, you'll need to follow these steps:rn rn Install and configure Nginx: First, you'll need to install Nginx on your server and configure it as a reverse proxy. You can follow the official Nginx installation guide for your Linux distrib
How To: Linux / Unix Move Directory Up One Level
To move a directory up one level in Linux/Unix, you can use the mv command with the .. syntax. Here's an example: Let's say you have a directory named mydir that you want to move up one level:rn rn rn /home/user/mydir/rn rn rnTo move mydir up one level to /home/user/ , you can use the followin
Bash Shell: Check If A Function Exists Or Not (Find Out If a Function Is Defined Or Not)
To check if a function exists or not in Bash shell, you can use the type command with the -t option. Here's an example:rn rn rn if ; then rn echo "myfunction is defined" rn else rn echo "myfunction is not defined" rn fi rn rn rnIn this example, we use the type command with the -t option to get th
Linux RPM: View Script That Run When You Install RPM Files
You can use the rpm command to view the scripts that run when you install an RPM package. RPM packages can contain scripts that run during the installation, upgrade, or removal of the package. Here's how to view the installation scripts for an RPM package:rn rn rn rpm -qp --scripts package .rpmrn
Linux: Display Binary Object Section Size, Text & Data Segment Information
You can use the size command on a binary object file to display the section sizes and the total size of the text and data segments. The size command displays the size of all the sections in the binary object file, along with their virtual addresses and names. By looking at the size of the .text a
Bash Shell Find Out If A Command Exists On UNIX / Linux System ($PATH) OR Not
To find out if a command exists on a Unix/Linux system, you can use the which or the type command. Both commands search for the specified command in the directories listed in the system's $PATH environment variable. Here's how to use the which command:rn rn rn which command_namern rn rnReplace co
Linux nginx: Chroot (Jail) Setup
Setting up a chroot jail for Nginx on Linux can help to increase the security of your web server. A chroot jail is a way to isolate a process and its children from the rest of the system by restricting their access to a specific directory tree. Here are the steps to set up a chroot jail for Nginx
Linux: Set OR Change The Library Path
In Linux, you can set or change the library path using the LD_LIBRARY_PATH environment variable. This variable is used by the dynamic linker/loader to locate shared libraries at runtime. Here's how to set or change the library path:rn rn To set the library path, open a terminal and enter the followi
tc: Linux HTTP Outgoing Traffic Shaping (Port 80 Traffic Shaping)
You can use tc to shape the outgoing HTTP traffic (i.e., port 80) on a Linux machine. Here is an example of how to do it: n n Identify the network interface that is connected to the internet. You can use the ifconfig command to get a list of all network interfaces and their IP addresses. n Create a
UNIX / Linux PGP TarBall File Signature Keys Verification
To verify the PGP signature of a tarball file in UNIX/Linux, you can follow these steps:rn rn Download both the tarball and the PGP signature file from the source. rn Import the signer's public key into your keyring. For example, if the signer's key is available on a keyserver, you can import it usi
Nginx: Custom Error 403 Page Not Working with IP Deny Configuration
If you are using the deny directive in your Nginx configuration to block access to certain IP addresses or ranges, you may find that your custom error page for HTTP 403 Forbidden errors is not being displayed for denied requests. This is because when a request is denied by the deny directive, Nginx
tcpdump: Monitor ALL eth1 Traffic Except My Own SSH Session
To monitor all traffic on eth1 except for your own SSH session using tcpdump , you can use the following command:rn rn rn sudo tcpdump - i eth1 not port 22 and not src <your IP address > and not dst <your IP address >rn rn rnHere's what each part of the command does:rn rn sudo tcpdump :
UNIX: Set Environment Variable
In UNIX-based operating systems (such as Linux and macOS), you can set environment variables using the "export" command. An environment variable is a dynamic value that can be accessed by programs and scripts running in the shell session. To set an environment variable, follow these steps:rn rn O
How To Save a File in Vi / Vim Text Editor
To save a file in Vi or Vim text editor, you can follow these steps:rn rn Press the Esc key to enter the command mode in Vi or Vim. rn Type ":w" followed by a space and then the filename to save the file under that name. For example, to save the file as "myfile.txt", you would type: rn rn rn rn :w m
[ERROR] /usr/local/libexec/mysqld: unknown variable ‘thread_concurrency=8’
The error message you are seeing indicates that the MySQL server is not able to recognize the "thread_concurrency" variable that is set to a value of 8 in the configuration file. The "thread_concurrency" variable was used in older versions of MySQL to control the number of threads that are used to p
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