Shell Script Wrapper Examples: Enhance the Ping and Host Commands

Posted on in Categories Linux, Shell scripting, UNIX last updated January 31, 2016

Shell script wrappers can make the *nix command more transparent to the user. The most common shell scripts are simple wrappers around third party or system binaries. A wrapper is nothing but a shell script that includes a system command or utility.

Linux and Unix like operating system can run both 32bit and 64bit specific versions of applications. You can write a wrapper script that can select and execute correct version on a 32bit or 64bit hardware platform. In cluster environment and High-Performance computing environment you may find 100s of wrapper scripts written in Perl, Shell, and Python to get cluster usage, setting up shared storage, submitting and managing jobs, backups, troubleshooting, invokes commands with specified arguments, sending stdout to stdout and stderr to stderr and much more.

In this post, I will explains how to create a shell wrapper to enhance the basic troubleshooting tool such as ping and host.

20 Examples: Make Sure Unix / Linux Configuration Files Are Free From Syntax Errors

Posted on in Categories Howto, Linux, Sys admin, Tips, UNIX last updated February 27, 2016

In Linux and UNIX system services are configured using various text files located in /etc/ or /usr/local/etc/ directory tree. A typical server system could have dozens of configuration files.You can check your configuration files for syntax errors without starting the server and validate all settings. In some cases, it is possible to to check the sanity of the specific data (such as keys) or directories (such as /var/lib/cache/). Text files are easier to manage remotely. You can use ssh and a text editor. If there is an error in configuration, the server may not start. It may result in a disaster. This post explains how to quickly how to find out a syntax error for popular servers and test configuration file for syntax errors.

30 Best Sources For Linux / *BSD / Unix Documentation On the Web

Posted on in Categories Debian Linux, FreeBSD, HP-UX, Linux, Linux distribution, OpenBSD, RedHat/Fedora Linux, Ubuntu Linux, UNIX last updated February 23, 2012

Man pages are written by sys-admin and developers for IT techs, and are intended more as a reference than as a how to. Man pages are very useful for people who are already familiar with Linux, Unix, and BSD operating systems. Use man pages when you just need to know the syntax for particular commands or configuration file, but they are not helpful for new Linux users. Man pages are not good for learning something new for the first time. Here are thirty best documentation sites on the web for learning Linux and Unix like operating systems.

Quick Tip: Find Hidden Processes and Ports [ Linux / Unix / Windows ]

Posted on in Categories Linux, UNIX last updated November 24, 2011

Unhide is a little handy forensic tool to find hidden processes and TCP/UDP ports by rootkits / LKMs or by another hidden technique. This tools works under both Linux / Unix, and MS-Windows operating systems. From the man page:

It detects hidden processes using three techniques:

  1. The proc technique consists of comparing /proc with the output of /bin/ps.
  2. The sys technique consists of comparing information gathered from /bin/ps with information gathered from system calls.
  3. The brute technique consists of bruteforcing the all process IDs. This technique is only available on Linux 2.6 kernels.