A Passionate Techie

In this article of the shell script debugging series, we will explain the third shell script debugging mode, that is shell tracing and look at some examples to demonstrate how it works, and how it can be used. The previous part of this series clearly throws light upon the two other shell script debugging modes:  verbose mode  and  syntax checking  mode with easy-to-understand examples of how to enable shell script debugging in these modes. Shell tracing simply means tracing the execution of the commands in a shell script. To switch on shell tracing, use the  -x  debugging option. This directs the shell to display all commands and their arguments on the terminal as they are executed. We will use the  sys_info.sh  shell script below, which briefly prints your system date and time, number of users logged in and the system uptime. However, it contains syntax errors that we need to find and correct. #!/bin/bash #script to print brief ...

Have you ever wondered where the various files contained inside a package are installed (located) in the Linux file system? In this article, we’ll show how to list all files installed from or present in a certain package or group of packages in Linux. This can help you to easily locate important package files like configurations files, documentation and more. Let’s look at the different methods of listing files in or installed from a package: How to List All Files of Installed Package in Linux You can use the  repoquery command  which is part of the  yum-utils to list files installed  on a CentOS/RHEL system from a given package. To install and use  yum-utils , run the commands below: # yum update # yum install yum-utils Now you can list files of an installed RPM package, for example  httpd  web server (note that the package name is case-sensitive). The  --installed  flag means installed packages and  -l  flags enabl...

sudo!! : Forgot to run a command with sudo? You need not re-write the whole command, just type "sudo!!" and the last command will run with sudo. 2. Python -m SimpleHTTPServer : Creates a simple web page for the current working directory over port 8000. 3. mtr : A command which is a combination of 'ping' and 'traceroute' command. 4. Ctrl+x+e : This key combination fires up, an editor in the terminal, instantaneously. 5. nl : Outputs the content of text file with lines Numbered. 6. shuf : Randomly selects line/file/folder from a file/folder. 7. ss : Outputs Socket Statistics. 8. Last: Want to know history of last logged in users? This command comes to rescue here. 9. curl ifconfig.me : Shows machine's external IP Address. 10. tree : Prints files and folders in tree like fashion, recursively. 11. Pstree : Prints running processes with child processes, recursively. 13. stat : Shows the status information of a file as well as of a file s...