xkcd 149 – punch this in your terminal:
cat > Makefile << _EOF SHELL=/bin/bash all: sandwich me: `echo $'\t'`@touch me a: `echo $'\t'`@if [ -e me ]; then rm me; touch a; fi sandwich: `echo $'\t'`@bash -c 'if [ -e a ]; then rm a; if [ \`whoami\` == "root" ] ; then echo "Ok"; else echo "Make it yourself"; fi; else echo "...?"; fi' _EOF
After that, try telling your command line to make you a sandwich, like this:
$ make me a sandwich Make it yourself $ sudo make me a sandwich [sudo] password for ivucica: Ok $
corrected on August 11 2009, to adjust for differences in Ubuntu’s shell 🙂
corrected on September 24 2015, to explicitly specify use of /bin/bash and fix breakage on Debian Jessie
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via blog.vucica.net