How to access shell environment variables in Perl script

Question: I would like to access several environment variables in my Perl script. How can I access shell variables from a Perl program? In some cases you may want to access shell environment variables (e.g., $PATH, $PWD, $HOME, $LANG) in your Perl script. While you can pass any needed environment variables to your Perl script […]
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How to search and replace a multi-line string in a file

Question: I have a text file in which I want to change multiple lines of text to something else, but without using a text editor. Is there a way to find and replace a multi-line string pattern from the Linux command line? Suppose you have a text file that looks like the following. Beginning of […]
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How to convert between local time and UNIX timestamp in Perl

Question: I need to convert readable date and time to a corresponding UNIX timestamp (i.e., Epoch time), or vice versa in a Perl program. Can you show me Perl code examples of converting date/time to UNIX timestamp, or conversely, converting UNIX timestamp to human-readable date and time? When your Perl script needs to deal with […]
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How to detect a Linux distribution in Perl

Question: I need to write a Perl program which contains Linux distro-dependent code. For that, the Perl program needs to be able to automatically detect what Linux distribution (e.g., Ubuntu, CentOS, Debian, Fedora, etc) it is running on, and what version number it is. How can I identify Linux distribution in Perl? If you want […]
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How to catch and handle a signal in Perl

Question: I need to handle an interrupt signal by using a custom signal handler in Perl. In general, how can I catch and handle various signals (e.g., INT, TERM) in a Perl program? As an asynchronous notification mechanism in the POSIX standard, a signal is sent by an operating system to a process to notify […]
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