trap 'handle_sigint' int
trap 'handle_sigint' INT
POSIX requires that signal names be given in uppercase:
The condition can be EXIT, 0 (equivalent to EXIT), or a signal specified using a symbolic name, without the SIG prefix, as listed in the tables of signal names in the <signal.h> header defined in XBD Headers; for example, HUP, INT, QUIT, TERM. Implementations may permit names with the SIG prefix or ignore case in signal names as an extension.
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