The content of this blog is my personal opinion only. Although I am an employee - currently of Nvidia, in the past of other companies such as Iagination Technologies, MIPS, Intellectual Ventures, Intel, AMD, Motorola, and Gould - I reveal this only so that the reader may account for any possible bias I may have towards my employer's products. The statements I make here in no way represent my employer's position, nor am I authorized to speak on behalf of my employer. In fact, this posting may not even represent my personal opinion, since occasionally I play devil's advocate.

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Wednesday, January 18, 2012

"system/command" versus "system command"

A lot of tools have a master command with subcommands. For example
hg clone ...
hg merge

cvs co
cvs update

git clomne
I think that the first place I encountered this was with mh. Or, since my friend MH says that mh did not have subcommands, I may have made the following change myself for mh. Why subcommands? I think mainly to avoid name collisions in the bin. Years ago, I kluged - I think it may have been the shell, whoever processes PATH - to search not just for "executable" on the PATH, but also "dir/executable". I.e. instead of saying
hg update
I colud have said
Not much of a difference. But it makes it easier for guys to code systems that have lots of subcommands. Also, for users of shells like bash and csh: !hg/update works, whereas "!hg update" doesn't (unless your shell has tweaks.

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