How does awk '!a[$0]++' work?
This one-liner removes duplicate lines from text input without pre-sorting. For example: $ cat >f q w e w r $ awk '!a[$0]++' <f q w e r $ The original code I have found on the internets read: awk '!_[$0]++' This was even more perplexing to me as I took _ to have a special meaning in awk, like in Perl, but it turned out to be just a name of an array. Now, I understand the logic behind the one-liner
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What is the difference between /opt and /usr/local?
According to the Filesystem Hierarchy Standard, /opt is for "the installation of add-on application software packages". /usr/local is "for use by the system administrator when installing software locally". These use cases seem pretty similar. Software not included with distributions usually is configured by default to install in either /usr/local or /opt with no particular rhyme or reason as to wh
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Preserve spacing and newline characters while using 'subshell' method
Trying to print up down arrow keys
