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Defining a variable with or without export
...l process. If you want a process to make use of this variable, use export, and run the process from that shell.
name=value
means the variable scope is restricted to the shell, and is not available to any other process. You would use this for (say) loop variables, temporary variables etc.
It's im...
How many random elements before MD5 produces collisions?
... quintillion 374 quadrillion 607 trillion 431 billion 768 million 211 thousand 456.
However if you keep all the hashes then the probability is a bit higher thanks to birthday paradox. To have a 50% chance of any hash colliding with any other hash you need 264 hashes. This means that to get a collis...
Why does the C++ STL not provide any “tree” containers?
Why does the C++ STL not provide any "tree" containers, and what's the best thing to use instead?
14 Answers
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How can I rollback a github repository to a specific commit?
...0 commits in it right now. I need to rollback the repository to commit 80, and remove all the subsequent ones.
6 Answers
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Git Gui: Perpetually getting “This repository currently has approximately 320 loose objects.”
...sible performance issue to you. This should be fixable by running this command from the command line:
cd path/to/your/git/repo
git gc --aggressive
From the output of git help gc:
Runs a number of housekeeping tasks within the current repository, such as compressing file revisions (to reduce disk s...
NSPredicate: filtering objects by day of NSDate property
...
Given a NSDate * startDate and endDate and a NSManagedObjectContext * moc:
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(date >= %@) AND (date <= %@)", startDate, endDate];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] ...
Should CSS always preceed Javascript?
...ownload each time a page is loaded.
To simulate reality, I included jQuery and the H5BP CSS (so there's a decent amount of script/CSS to parse)
Set up two pages - one with CSS before script, one with CSS after script.
Recorded how long it took for the external script in the <head> to execute
R...
“did you run git update-server-info” error on a Github repository
I'm using the github Gui from their website to manage my repos, and I'm getting the following error:
20 Answers
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How to check certificate name and alias in keystore files?
I have a bunch of .keystore files and need to find one with specific CN and alias. Is there a way to do it with keytool, jarsigner or some other tool? I found a way to check if specific keystore was used to sign a specific apk, but I also need to get the alias and certificate name in each of the fil...
Remove DEFINER clause from MySQL Dumps
...them after the dump file is created.
Open the dump file in a text editor and replace all occurrences of DEFINER=root@localhost with an empty string ""
Edit the dump (or pipe the output) using perl:
perl -p -i.bak -e "s/DEFINER=\`\w.*\`@\`\d[0-3].*[0-3]\`//g" mydatabase.sql
Pipe the output throug...