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How do I delete an exported environment variable?
Before installing gnuplot, I set the environment variable GNUPLOT_DRIVER_DIR = /home/gnuplot/build/src . During the installation, something went wrong.
...
“open/close” SqlConnection or keep open?
...ion()) {} public SqlConnection GetConnection() { return new SqlConnection(_connectionString); }
– ganders
Jan 23 at 17:12
...
Returning an array using C
...ype; the function actually receives a pointer type:
void foo(char *a, size_t asize)
{
// do something with a
}
int bar(void)
{
char str[6] = "Hello";
foo(str, sizeof str);
}
In the call to foo, the expression str is converted from type char [6] to char *, which is why the first parameter o...
Give all the permissions to a user on a DB
...user needs access to the database, obviously:
GRANT CONNECT ON DATABASE my_db TO my_user;
And (at least) the USAGE privilege on the schema:
GRANT USAGE ON SCHEMA public TO my_user;
Or grant USAGE on all custom schemas:
DO
$$
BEGIN
-- RAISE NOTICE '%', ( -- use instead of EXECUTE to see ge...
What's the difference between Perl's backticks, system, and exec?
...t, and don't want to wait for it to return. system is really just
sub my_system {
die "could not fork\n" unless defined(my $pid = fork);
return waitpid $pid, 0 if $pid; #parent waits for child
exec @_; #replace child with new process
}
You may also want to read the waitpid and perli...
What are the differences between Deferred, Promise and Future in JavaScript?
...es from [Functional Reactive Programming|haskell.org/haskellwiki/Functional_Reactive_Programming], which is a technique for flattening callbacks."
– fncomp
Feb 11 '13 at 5:32
2
...
Integrate ZXing in Android Studio
...tIntegrator(this);
integrator.setDesiredBarcodeFormats(IntentIntegrator.ONE_D_CODE_TYPES);
integrator.setPrompt("Scan a barcode");
integrator.setCameraId(0); // Use a specific camera of the device
integrator.setBeepEnabled(false);
integrator.setBarcodeImageEnabled(true);
integrator.initiateScan();
...
Difference between Destroy and Delete
...ary key, and no callbacks are executed.
To enforce the object's before_destroy and after_destroy callbacks or any :dependent association options, use #destroy.
ActiveRecord::Persistence.destroy
Deletes the record in the database and freezes this instance to reflect that no changes should b...
ActiveRecord: size vs count
...e a new record without going through the relation, i.e. Comment.create(post_id: post.id), your post.comments.size will not be up to date, while post.comments.count will. So just be careful.
– mrbrdo
Mar 31 '13 at 19:52
...
What is a semaphore?
...interestingly it has already been used: albahari.com/threading/part2.aspx#_Semaphore
– Igor Brejc
Mar 27 '15 at 8:50
...