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How do I read the first line of a file using cat?
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Does head read the entire file and cut it, or does it read only the 1 line?
– CMCDragonkai
May 1 '15 at 2:53
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Python memoising/deferred lookup property decorator
...because it avoids sticking extra attributes on objects, and once activated does not waste time checking for attribute presence, etc.:
import functools
class lazy_property(object):
'''
meant to be used for lazy evaluation of an object attribute.
property should represent non-mutable dat...
Why is iterating through a large Django QuerySet consuming massive amounts of memory?
...nd the results come spilling out.
From my reading of the docs, iterator() does nothing more than bypass QuerySet's internal caching mechanisms. I think it might make sense for it to a do a one-by-one thing, but that would conversely require ten-million individual hits on your database. Maybe not ...
SVN: Is there a way to mark a file as “do not commit”?
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Subversion does not have a built-in "do not commit" / "ignore on commit" feature, as of February 2016 / version 1.9. This answer is a non-ideal command-line workaround
As the OP states, TortoiseSVN has a built in changelist, "ignore-on...
Is there a way to get the git root directory in one command?
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This is what hg root does. It prints out the top-level directory of your checked out repository. It doesn't switch you to it (and it couldn't, in fact, do so because of how the whole concept of current directory and your shell interact).
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Defining a variable with or without export
...temporary variables etc.
It's important to note that exporting a variable doesn't make it available to parent processes. That is, specifying and exporting a variable in a spawned process doesn't make it available in the process that launched it.
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How to Flatten a Multidimensional Array?
... [x] => X
[y] => Y
[p] => P
[q] => Q
)
But it does not work when the outer array has non numeric keys. In that case, you will have to call array_values first.
$c = ["a" => ["x" => "X", "y" => "Y"], "b" => ["p" => "P", "q" => "Q"]];
print_r(array_merge(...
How to “hibernate” a process in Linux by storing its memory to disk and restoring it later?
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I used to maintain CryoPID, which is a program that does exactly what you are talking about. It writes the contents of a program's address space, VDSO, file descriptor references and states to a file that can later be reconstructed. CryoPID started when there were no usable ho...
How can I reconcile detached HEAD with master/origin?
...tive rebase operation). Usually you would use git rebase --abort, but that does some extra resetting that you probably want to avoid (it moves HEAD back to the original branch and resets it back to the original commit, which will undo some of the work we did above).
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C fopen vs open
...at may turn out to be a lot faster than what you're doing with open.
fopen does line ending translation if the file is not opened in binary mode, which can be very helpful if your program is ever ported to a non-Unix environment (though the world appears to be converging on LF-only (except IETF text...