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How can I use grep to show just filenames on Linux?
...andard:
-l
(The letter ell.) Write only the names of files containing selected
lines to standard output. Pathnames are written once per file searched.
If the standard input is searched, a pathname of (standard input) will
be written, in the POSIX locale. In other locales, standard i...
Is it a good idea to index datetime field in mysql?
...ne table with 4 million records. Most of my queries use datetime clause to select data. Is it a good idea to index datetime fields in mysql database?
...
What does Redis do when it runs out of memory?
...s reached Redis will try to remove keys
# according to the eviction policy selected (see maxmemory-policy).
#
# If Redis can't remove keys according to the policy, or if the policy is
# set to 'noeviction', Redis will start to reply with errors to commands
# that would use more memory, like SET, LPU...
How To Create Table with Identity Column
...ues ('NULL','address2')
insert into teppp ( addresss) values ('address3')
select * from teppp
null string , address1
NULL,address2
NULL,address3
If you try inserting same values as below:
insert into teppp ( name,addresss) values ('','address4')
insert into teppp ( name,addresss) values ('NULL',...
Android 4.3 Bluetooth Low Energy unstable
... I have a work around for being unable to unpair. 1) go to your bt menu, select unpair, remove the ble device from the area or depower it, select the ble device in the bt menu and it'll try to pair and fail, then reset bluetooth. Upon reset the device will be unpaired.
– Chr...
live output from subprocess command
...ptimization: If we are only using one pipe, or no pipe at
# all, using select() or threads is unnecessary.
if [self.stdin, self.stdout, self.stderr].count(None) >= 2:
But, alas, here we've made at least two, and maybe three, different pipes, so the count(None) returns either 1 or 0. We...
Purpose of memory alignment
...y you have a struct in memory that looks like this:
struct mystruct {
char c; // one byte
int i; // four bytes
short s; // two bytes
}
On a 32-bit processor it would most likely be aligned like shown here:
The processor can read each of these members in one transaction.
Say you...
autolayout - make height of view relative to half superview height
...lso need to setup bottom, left, and right constraints, like normal)
. Then select the constraint and navigate to the Attribute inspector:
Then you can adjust the multiplier. If you want it 50% of the super view leave it at 1, since it is aligned per the super's center. This is also a great way to...
How do I extract a sub-hash from a hash?
...e same:
h1 = {:a => :A, :b => :B, :c => :C, :d => :D}
h2 = h1.select {|key, value| [:b, :d, :e, :f].include?(key) } # => {:b=>:B, :d=>:D}
h1 = Hash[h1.to_a - h2.to_a] # => {:a=>:A, :c=>:C}
And if you want to patch that into the Hash class:
class Hash
def extract...
getting the X/Y coordinates of a mouse click on an image with jQuery [duplicate]
...
For sure better than the selected one.
– Mangirdas Skripka
Jan 10 '15 at 11:43
...