Quick Bytes IT Stuff

 Reading files is basic and a must when working on the terminal in Linux or command line. There are a lot of ways to do this, a simple task but quite a few ways to accomplish it. Nano, vi/vim the most common editor in Linux that is part of the package in most Linux flavors if not all. In nano editor, while the file is open pressing "alt + n", will display the line numbering on the left side of the screen. Example image: In vi or vim, opening the file and typing the command: "set nu" or "set number" will also view the lines on the left side of the screen. Example image:   Or from the command line itself using "cat -n any_file_name.txt" will also view line numbers the -n is a parameter on cat to view or include the line numbers when displaying the file. Example image: less -N, command will also produce same result. Or just use nl , "man nl" shows:  NAME        nl - number lines of files It comes pre-installed in almost any Linux flavors,...

 Displaying GUI Boxes in Linux Bash scripts can be done easily using whiptail. In Windows OS, msgbox, inptubox is quite helpful on VBA, Visual Basic and even in .NET world. Displaying Graphical boxes in Linux bash scripting is quite simple to do. To navigate on this GUI boxes, used "Tabs","Arrow Keys" and "Space Bar" as enter key. Here's a simple example of Whiptail that display GUI Boxes and ping the sites that are selected. #!/bin/bash # Step 1: Checkbox URL menu CHOICES=$(whiptail --title "Checkbox Ping URLs Example" \   --checklist "Select one or more options:" 15 50 5 \   "ping -c 2 bing.com;" "Ping bing" OFF \   "ping -c 2 duckduckgo.com;" "Ping ddg" OFF \   "ping -c 2 search.com;" "Ping search" OFF \   "ping -c 2 google.com" "Ping google" OFF \   3>&1 1>&2 2>&3) # Exit gracefully if nothing was selected or user pressed Cancel ...

 How to find or identify empty directories or files in Linux? It can be done easily with find command itself. Here's the syntax and how to test. mkdir test_empty cd test_empty create some dummy directories: mkdir {dummydir1,dummydir2,dummydir3} then create some empty files: touch {file1empty,file2empty,file3empty} To find empty directories: find . -type d -empty To find empty files: find . -type f -empty All directories and files will be shown since they are empty. Add some text to the file: echo "Test" > file1empty Run again the command: find . -type f -empty file1empty will not be on the list since the file has some text. Move the file1empty to dummydir1. mv file1empty dummydir1 Run the command to find empty directories: find . -type d -empty dummydir1 will not be displayed since file1empty is inside of it. How to remove or delete empty directories or files? In production or any environment, make sure you know what you are doing. In a testing environment, it can be d...

How to hide a file in Windows? How to set a read only file in Windows? Or set a read only file in Windows and hide it. Setting a file to read only or hiding a file in Windows, or doing both at the same time, can be done using Command Prompt or using PowerShell. Example commands: Hiding a file in Windows using PowerShell: (Get-Item "C:\file_example.txt").Attributes = 'Hidden' Setting a read-only file: (Get-Item "C:\file_example.txt").Attributes = 'ReadOnly' Set both read-only and hidden attributes to a file. (Get-Item "C:\file_example.txt").Attributes = 'Hidden, ReadOnly' How to reset the attributes or remove the attributes that was set? (Get-Item "C:\file_example.txt").Attributes = 'Normal' Hiding a file using command Prompt: c:\attrib +h "file_example.txt" Setting a read-only file: c:\attrib +h "file_example.txt" Set both read-only and hidden attributes to a file. c:\attrib +h +r "file_exa...

Automation is a buzzword in today's technology; it makes things faster, effortless, and most of all ease the burden of system administrators. However, automation should be tested thoroughly to avoid any unforeseen circumstances or else instead of making life easier it might deliver some nightmares. For example, removing log files to save space or remove any unwanted or old log files to make room for new files; this task can be done manually or using some automation via a script. In Linux, cron jobs that fires automatically as per schedule is quite ideal to automate removing or deleting log files. This can also be done manually, by simply logging in to the server and delete files. There is nothing wrong in deleting manually but would not be ideal if the operation of the server is operating day and night.  There might be a chance that the operation will halt if there is no more room to write the log files. Or simply when there is some issue and wanted to troubleshoot; if log files ar...

If a Linux box VM, WSL or a physical server is unable to connect to Network, one possible issue is the network interface is not UP. Typing:   ip address show   Or:   ip a s  The output will show which interfaces are UP. If the output shows like:  eth0: <BROADCAST, MULTICAST, UP, LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 UP after multicast means that the interface is not disabled on the OS or administratively enabled LOWER_UP means that a cable is connected  and is able and is able to find an active switch port  Running this command below: tcpdump -D The output will also show that the interface is Up, Running and connected. Example: 1. eth0 [Up, Running, Connected] Basic commands that will help to save the day if ever there is some network or connectivity issues. zenity, dialog, can also be used to generate GUI boxes. However, whiptail still the best for minimal footprint and might come as a default for Server Distros OS. That's...

HAProxy is an open-software used as a high-performance load balancer and reverse proxy for TCP. To check whether the proxy config before reloading or restarting the HAProxy service can be done via this command:  haproxy -c -f /etc/haproxy/haproxy.cfg It will show 'configuration file is valid' if everything is okay or the config file syntax is valid. However, the command cannot check whether it can bind the port, or bind the socket. Example, typing: systemctl reload haproxy to reload the new config file. And to check whether the reload is successful or not status of the service can be checked. Typing, systemctl status haproxy to check the status and if it shows Reload: failed then binding issues or other errors causes reloading to fail. Or some alert is shown as Binding like /etc/haproxy/haproxy.cfg cannot bind socket or cannot assign requested address for 192.168.x.x. IP Technically, the error is already giving some hints that the IP on the HAProxy config file cannot be used fo...