A website stopped opening in browser, giving the error that the SSL certificate was either invalid or had expired.
Checking the website with wget,
$ wget https://www.example.com --2018-01-14 16:58:36-- https://www.example.com/ Resolving www.example.com (www.example.com)... 198.51.100.12, 2001:db8:1221:2341:f03c:f27b:12fa:2123 Connecting to www.example.com (www.example.com)|198.51.100.12|:443...… Read more
Problem: After an image is developed and edited by image editing software and saved in a format like JPEG, it does not have the Exif metadata.
Surprisingly, quite a few image editing programs do not preserve the Exif metadata of images and attempts to read Exif get outputs like this.… Read more
After a photograph has been taken and processed, it might be necessary to add IPTC metadata before it can be published. If your image editing software does not support adding of IPTC metadata to the image, you can accomplish this is by using the exiv2 command in Linux.… Read more
While using bc for calculations, the value of π is sometimes required. Sure, you might remember it as 3.1416, but it is better to use a higher precision value. And it's quite simple to do that.
First, we need to start bc with the option -l (ell) to use the standard math library.… Read more
While executing the dig command, the sendmsg() failed: Operation not permitted
error was printed.
$ dig example.com ../../../../lib/isc/unix/net.c:581: sendmsg() failed: Operation not permitted ../../../../lib/isc/unix/net.c:581: sendmsg() failed: Operation not permitted ...
The error was resolved after adding the following iptables rules.… Read more
Given an nginx web server log file, we might like to know who are the visitors to our website. One can go line by line through the log file, but that is tedious. It would be nice if we can get one line per client visiting the website, giving the IP address of the visitor and how many times that client has visited.… Read more
A signed APK of an Android app was built using the Android Studio. When we tried to download the signed APK to a device using the adb command, the command failed with the error, INSTALL_PARSE_FAILED_NO_CERTIFICATES.
$ adb install app-release.apk app-release.apk: 1 file pushed.… Read more
While trying to open sitemap.xml of a site served by nginx and built using Drupal CMS, the 404 Not Found
error was received. The nginx log file, error.log gave the error as, 80 open() sitemap.xml failed (2: No such file or directory)
.… Read more
While running optipng on a png file, the following error was obtained,
Error: Can't back up the existing output file
The file was not having the write permission. Once, the write mode bit for the file was set, optipng worked fine.… Read more
