Shell Scripting

Shell Scripting

A shell script is a script written for the shell, or command line interpreter, of an operating system. It is often considered a simple domain-specific programming language. Typical operations performed by shell scripts include file manipulation, program execution, and printing text. Usually, shell script refers to scripts written for a Unix shell, while COMMAND.COM (DOS) and cmd.exe (Windows) command line scripts are usually called batch files, but here properties of both are discussed.

Many shell script interpreters double as command line interface, such as the various Unix shells, Windows PowerShell or the MS-DOS COMMAND.COM. Others, such as AppleScript, add scripting capability to computing environments without requiring a command line interface. Other examples of programming languages primarily intended for shell scripting include DCL and JCL.

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PHP Session File Hacks

What they say about kung-fu is true..

It can be attained by anyone through hard work over time. You can become as good as the amount of work you put in. Here’s a short look at a basic technique that I use. Simply reverse engineering the source code and taking notes along the way…

static void php_session_send_cookie(TSRMLS_D)
  if (SG(headers_sent)) {
          if (output_start_filename) {
                  php_error_docref(NULL TSRMLS_CC, E_WARNING, "Cannot send session cookie - headers already sent by (output started at %s:%d)",
                          output_start_filename, output_start_lineno);
          } else {
                  php_error_docref(NULL TSRMLS_CC, E_WARNING, "Cannot send session cookie - headers already sent");
          }
          return;
  }
 
  /* URL encode session_name and id because they might be user supplied */
  e_session_name = php_url_encode(PS(session_name), strlen(PS(session_name)), NULL);

· session  ·  RSS | 8:00 PM

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Crazy POWERFUL Bash Prompt

This amazing bash linux prompt does more than meets the eye. If you want to know how to become really good with technology, linux is the secret sauce behind the AskApache articles. Open Source is elixir of the web. Thanks to everyone who helped me for the past 20 years. I use linux/bsd because homey don’t play, so this is geared to be as productive a prompt as I can make it.

Don’t have much time.. or just don’t care? Not a problem, here are the 3 lines to copy and paste – you can just paste them right in your shell to test it, or add to a startup script.

export AA_P="export PVE=\"\\033[m\\033[38;5;2m\"\$(( \`sed -n \"s/MemFree:[\\t ]\\+\\([0-9]\\+\\) kB/\\1/p\" /proc/meminfo\` / 1024 ))\"\\033[38;5;22m/\"\$((\`sed -n \"s/MemTotal:[\\t ]\\+\\([0-9]\\+\\) kB/\\1/p\" /proc/meminfo\`/ 1024 ))MB\"\\t\\033[m\\033[38;5;55m\$(< /proc/loadavg)\\033[m\";echo -en \"\""
export PROMPT_COMMAND="history -a;((\$SECONDS % 10==0 ))&&eval \"\$AA_P\";echo -en \"\$PVE\";"
export PS1="\\[\\e[m\\n\\e[1;30m\\][\$\$:\$PPID \\j:\\!\\[\\e[1;30m\\]]\\[\\e[0;36m\\] \\T \\d \\[\\e[1;30m\\][\\[\\e[1;34m\\]\\u@\\H\\[\\e[1;30m\\]:\\[\\e[0;37m\\]\${SSH_TTY} \\[\\e[0;32m\\]+\${SHLVL}\\[\\e[1;30m\\]] \\[\\e[1;37m\\]\\w\\[\\e[0;37m\\] \\n(\$SHLVL:\\!)\\\$ " && eval $AA_P

· Prompt  ·  RSS | 3:02 PM

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HOWTO: Uninstall CPANEL over SSH

The following is just a quick reference of some of the commands I used to uninstall cpanel. This is for advanced users of the shell. If you aren’t that advanced and you run a single one of these commands without fully understanding it, you will probably kill your server, probably lose everything on it permanently, probably not have a website or email for weeks.. So backup all your data FIRST. Also, if you aren’t 100% sure you won’t run into problems, you should contact your hosts technical support – but be prepared for some MAJOR negativity.. cpanel makes things very easy for hosts, and the last thing tech support wants is to fix a server broken by someone who doesn’t know what they are doing.

· Uninstalling  ·  RSS | 2:55 PM

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30x Faster WP-Super Cache Site Speed

NOT a typo.. 30x is measurable, well-documented, and easily tested. This is what open-source is about. I haven’t had time to post much the past year, I’m always working! So I wanted to make up for that by publishing an article on a topic that would blow your mind and be something that you could actually start using and really get some benefit out of it. This is one of those articles that the majority of web hosting companies would love to see in paperback, so they could burn it.

· 30x  ·  RSS | 11:43 AM

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Advanced WordPress wp-config.php Tweaks

The bottom line for this article is that I want to make WordPress as fast, secure, and easy to install, run, and manage because I am using it more and more for client production sites, I will work for days in order to solve an issue so that I never have to spend time on that issue again. Time is money in this industry and that is ultimately (time) what there is to gain by tweaking WordPress.

Note: I spent no time on readability, this is primarily a read the code and figure it out article.. This is for advanced users looking for a reference or discussion and for those of you looking to advance. Feedback would be great if you make it that far..

· Tweaks  ·  RSS | 3:23 AM

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Optimize a Website for Speed, Security, and Easy Management

Learn how to setup, configure, secure, optimize, and create a low-maintenance website the AskApache way. I’m piecing together all the hacks, tricks, methods, and ideas discussed throughout this blog and all across Netdom and glueing them all together to show you how to have the most optimized, crazy fastest, and best website setup I can think of.

· htaccess  ·  RSS | 8:45 PM

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Custom bash_profile for Advanced Shell Users

Looking for some advanced uses for the shell? Here is some of my best. The shell is where 70% of my work takes place, and I have at least one terminal open almost 100% of the time, for viewing tailing color-coded logs, and of course for the SSH Tunnels that I use to route various networking through, like my email. So I decided that to standardize and create a bash_profile containing the most time-saving and helpful functions that I could use on all the various hosting environments would really be some sweet sugar, so here is my constant Work-in-progress.

It works for all shells I encounter, including BackTrack, Debian, Knoppix, Arch Linux, etc. Also works for many hosting environments I use including DreamHost, HostGator, WiredTree, and pretty much any linux VPS.

I also rely on this heavily from within shell scripts I write to access all the functions and stuff in this .bash_profile, and to do that I just do like:

#!/bin/bash
 
source ~/.bash_profile &>/dev/nulll
 
pm "PM is a function to output nice messages with color"
yn "Are you enjoying the shell" && pm "Thats great!" || pm "Perhaps you're better suited for DOS"
yn "Show Calendar" && aa_calendar
yn "Show Fortune" && aa_fortune

· profile  ·  RSS | 3:32 PM

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Optimizing Servers and Processes for Speed with ionice, nice, ulimit

To prepare for several upcoming articles on AskApache that are focused on optimizing Servers and Sites from a server admin level, here is an article to introduce the main tools that we will be using. These tools are used to optimize CPU time for each process using nice and renice, and other tools like ionice are used to optimize the Disk IO, or Disk speed / Disk traffic for each process. Then you can make sure your mysqld and httpd processes are always fast and prioritized.

· optimize  ·  RSS | 1:41 AM

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PHP and AJAX shell console

Ever wanted to execute commands on your server through php? Now you can. I’m calling this file (see below) shell.php and it allows you to run commands on your web server with the same permissions that your php executable has.

· shell  ·  RSS | 9:01 PM

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Mirroring an Entire Site using Rsync over SSH

Sometimes there is an urgent need for creating an exact duplicate or “mirror” of a web site on a separate server. This could be needed for creating Round Robin Setups, Load-Balancing, Failovers, or for just plain vanilla backups. In the past I have used a lot of different methods to copy data from one server to another, including creating an archive of the whole directory and then using scp to send the file over, creating an archive and then encrypting it and then sending that file over using ftp, curl, etc., and my persistence at learning new ways to do things has paid off because now I use rsync to keep an exact replica of the entire directory on an external server, without having to use all the CPU and resources of other mirroring methods.

· SSH  ·  RSS | 7:40 AM

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Chmod, Umask, Stat, Fileperms, and File Permissions

Unix file permissions are one of the more difficult subjects to grasp.. Well, ok maybe “grasp” isn’t the word.. Master is the right word.. Unix file permissions is a hard topic to fully master, mainly I think because there aren’t many instances when a computer user encounters them. I’ve done a lot of research on it the past couple weeks… and now here’s everything I’ve learned so far.. cuz you guys AskApache Regs Rock!

· File  ·  RSS | 6:16 AM

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Serve External Javascript Files locally for Increased Speed

One way I speed up AskApache.com is by downloading external third-party javascript files to host on my own server instead of externally. In addition to the obvious speed boost, this lets you configure the caching and compression settings for the files.

· javascript  ·  RSS | 2:55 AM

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Pimp out your FeedBurner Count

I’ve had a lot of people ask about the FeedBurner FeedCount image on AskApache. Specifically how to set it up with custom messages and different colors each page view… It is pretty sweet..

· count  ·  RSS | 4:50 AM

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Elite Log File Scrolling with Color Syntax

Scrolls the latest log entries for multiple log files to the current screen or to any other monitor or TTY in color using syntax highlighting, making debugging easier and saving a lot of time for multi-monitor workstations.

· errorlog  ·  RSS | 12:56 AM

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Encrypted WordPress / phpBB Backups

Enter your DOMAIN_ROOT and the location of your wp-config.php or config.php, and this script finds all the mysql settings by parsing the phpbb or wordpress config file, then creates GPG encrypted backups, and saves your settings for future automation.

· unix  ·  RSS | 12:28 PM

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Automated Folder Backup Shell-Script

This simple unix shell script automatically creates backups of a specific folder at regular hourly, nightly, weekly, and monthly intervals. Instead of the usual method for copying directory trees using tar with fifo, pipes, rsync, or NFS methods this script uses cpio which is much much faster and has cool options like saving m/a/c times, symlinks, relative paths, and weird file names.

· archive  ·  RSS | 1:22 AM

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Search And Replace shell script helpful for Upgrades

Search all files in a directory, replacing all occurances of string with a replacement string.

· Replace  ·  RSS | 1:09 AM

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IP Abuse Detection for DreamHost

Scan Apache logs for IP address that are probably evil, then generates an .htaccess file to DENY them all.

RSS | 9:46 AM

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Log all .htaccess/.htpasswd logins

Learn how to log and debug usernames and passwords used to login to a htaccess basic authorization protected website using php. This article is BOSS and will show you how to fully take control of this aspect of security using php and .htaccess, I don’t believe you will find instructions to do this anywhere else on the net.

· authorization  ·  RSS | 9:20 PM

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Apache Environment Variables CGI Script

My improved version of the common printenv / test-cgi scripts for debugging Apache environment variables set in .htaccess files

RSS | 11:40 AM

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