Tuesday, August 5, 2008
Monday, August 4, 2008
Thursday, July 31, 2008
Unix 0, 1, and 2 Redirection
What does “> /dev/null 2>&1″ mean?
"There are three standard sources of input and output for a program. Standard input usually comes from the keyboard if it’s an interactive program, or from another program if it’s processing the other program’s output. The program usually prints to standard output, and sometimes prints to standard error. These three file descriptors (you can think of them as “data pipes”) are often called STDIN, STDOUT, and STDERR.
Sometimes they’re not named, they’re numbered! The built-in numberings for them are 0, 1, and 2, in that order. By default, if you don’t name or number one [of them] explicitly, you’re talking about STDOUT. (emphasis added)
Given that context, you can see the command above is redirecting standard output into /dev/null, which is a place you can dump anything you don’t want (often called the bit-bucket), then redirecting standard error into standard output (you have to put an & in front of the destination when you do this).
The short explanation, therefore, is “all output from this command should be shoved into a black hole.” That’s one good way to make a program be really quiet!"
"There are three standard sources of input and output for a program. Standard input usually comes from the keyboard if it’s an interactive program, or from another program if it’s processing the other program’s output. The program usually prints to standard output, and sometimes prints to standard error. These three file descriptors (you can think of them as “data pipes”) are often called STDIN, STDOUT, and STDERR.
Sometimes they’re not named, they’re numbered! The built-in numberings for them are 0, 1, and 2, in that order. By default, if you don’t name or number one [of them] explicitly, you’re talking about STDOUT. (emphasis added)
Given that context, you can see the command above is redirecting standard output into /dev/null, which is a place you can dump anything you don’t want (often called the bit-bucket), then redirecting standard error into standard output (you have to put an & in front of the destination when you do this).
The short explanation, therefore, is “all output from this command should be shoved into a black hole.” That’s one good way to make a program be really quiet!"
Tuesday, July 29, 2008
Friday, July 18, 2008
Wednesday, July 16, 2008
Friday, July 11, 2008
every morning should start like this...
Earlier this morning, with coffee in hand and cats at my feet...
So I re-connected with my senior year AP English Lit teacher Laura Nicosia via none other than a recent obsession with twitter! Best use of those 140 characters as yet. She has a blog that chronicles her foray into web 2.0 technologies, which is great because its nice to be alongside aspiring female nerds fervently indulging their inner-technophiles.
So I re-connected with my senior year AP English Lit teacher Laura Nicosia via none other than a recent obsession with twitter! Best use of those 140 characters as yet. She has a blog that chronicles her foray into web 2.0 technologies, which is great because its nice to be alongside aspiring female nerds fervently indulging their inner-technophiles.
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