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Test if a variable is set in bash when using “set -o nounset”
...sh
$ /bin/bash --version | head -1
GNU bash, version 4.1.2(1)-release (x86_64-redhat-linux-gnu)
$ set -o nounset
If you want a non-interactive script to print an error and exit if a variable is null or not set:
$ [[ "${HOME:?}" ]]
$ [[ "${IAMUNBOUND:?}" ]]
bash: IAMUNBOUND: parameter null or not...
How to create multidimensional array
...uctures and Algorithms with JavaScript
The Good Parts (O’Reilly, p. 64). Crockford extends the JavaScript
array object with a function that sets the number of rows and columns
and sets each value to a value passed to the function. Here is his
definition:
Array.matrix = function(numrow...
What is the significance of ProjectTypeGuids tag in the visual studio project file
...
</PropertyGroup>
But for some special projects (such as some database projects) and projects lacking a file (such as Web Site projects), the project type is stored also in the solution file:
Microsoft Visual Studio Solution File, Format Version 10.00
# Visual Studio 2008
Project("{F184B08...
How to get overall CPU usage (e.g. 57%) on Linux [closed]
...o apt-get install sysstat
Linux 3.0.0-13-generic (ws025) 02/10/2012 _x86_64_ (2 CPU)
03:33:26 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle
03:33:26 PM all 2.39 0.04 0.19 0.34 0.00 0.01 0.00 0.00 97.03
Then some cutor grepto pars...
What does the git index contain EXACTLY?
...documented in man git-merge:
0: regular file, not in a merge conflict
1: base
2: ours
3: theirs
During a merge conflict, all stages from 1-3 are stored in the index
to allow operations like git checkout --ours.
If you git add, then a stage 0 is added to the index for the path,
and Git will know...
What is meant by 'first class object'?
...
Sander VersluysSander Versluys
64.9k2222 gold badges7979 silver badges8888 bronze badges
...
get NSDate today, yesterday, this Week, last Week, this Month, last Month… variables
...s taken from Google
NSDate *yesterday = [today dateByAddingTimeInterval: -86400.0];
NSDate *thisWeek = [today dateByAddingTimeInterval: -604800.0];
NSDate *lastWeek = [today dateByAddingTimeInterval: -1209600.0];
// To get the correct number of seconds in each month use NSCalendar
NSDate *thisMon...
What does enctype='multipart/form-data' mean?
...le2=a.html&file3=binary
Clearly the file data was not sent, only the basenames. So this cannot be used for files.
As for the text field, we see that usual printable characters like a and b were sent in one byte, while non-printable ones like 0xCF and 0x89 took up 3 bytes each: %CF%89!
Compar...
How do you read CSS rule values with JavaScript?
...
Note that this doesn't work since GC versio 64.0: stackoverflow.com/questions/48753691/…
– Shalev Levi
Feb 21 at 11:13
| ...
Is there an auto increment in sqlite?
...n alias for the
ROWID (except in WITHOUT ROWID tables) which is always a 64-bit signed
integer.
On an INSERT, if the ROWID or INTEGER PRIMARY KEY column is not
explicitly given a value, then it will be filled automatically with an
unused integer, usually one more than the largest ROWID cur...