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Test if a variable is set in bash when using “set -o nounset”
...ER:-}
if [ ! -z ${VALUE} ];
then echo "yo"
fi
echo "whatever"
In this case, VALUE ends up being an empty string if WHATEVER is not set. We're using the {parameter:-word} expansion, which you can look up in man bash under "Parameter Expansion".
...
memcpy() vs memmove()
...() and memmove() , and I have read the text that memcpy() doesn't take care of the overlapping source and destination whereas memmove() does.
...
How to print a string in fixed width?
...rect, but people looking at this should prefer the new format syntax.
You can use string formatting like this:
>>> print '%5s' % 'aa'
aa
>>> print '%5s' % 'aaa'
aaa
>>> print '%5s' % 'aaaa'
aaaa
>>> print '%5s' % 'aaaaa'
aaaaa
Basically:
the % characte...
PHP Sort Array By SubArray Value
...paceship operator <=> instead of subtraction to prevent overflow/truncation problems.
usort($array, function ($a, $b) {
return $a['optionNumber'] <=> $b['optionNumber'];
});
share
|
...
SVN+SSH, not having to do ssh-add every time? (Mac OS)
...y that this is a Mac thing, not a universal Unix thing. On Ubuntu, ssh-add can't take a -K argument.
– Mark Amery
Jan 14 '14 at 14:48
2
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Git fails when pushing commit to github
...po (edited- or the size of a particular file) you are trying to push.
Basically I was able to create new repos and push them to github. But an existing one would not work.
The HTTP error code seems to back me up it is a 'Length Required' error. So maybe it is too large to calc or greated that the...
Is it a bad practice to use negative margins in Android?
...ive margins had unspecified behavior.
In 2011, @RomainGuy stated that you can use negative margins on LinearLayout and RelativeLayout.
In 2016, @RomainGuy stated that they have never been officially supported and won't be supported by ConstraintLayout.
It is easy to work around this limitation ...
How to delete multiple files at once in Bash on Linux?
...
Bash supports all sorts of wildcards and expansions.
Your exact case would be handled by brace expansion, like so:
$ rm -rf abc.log.2012-03-{14,27,28}
The above would expand to a single command with all three arguments, and be equivalent to typing:
$ ...
Check if a folder exist in a directory and create them using C#
How can I check if directory C:/ contains a folder named MP_Upload , and if it does not exist, create the folder automatically?
...
Regular Expressions: Is there an AND operator?
Obviously, you can use the | (pipe?) to represent OR , but is there a way to represent AND as well?
12 Answers
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