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How can I check if a command exists in a shell script? [duplicate]
I am writing my first shell script. In my script I would like to check if a certain command exists, and if not, install the executable. How would I check if this command exists?
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How to check if any flags of a flag combination are set?
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If you want to know if letter has any of the letters in AB you must use the AND & operator. Something like:
if ((letter & Letters.AB) != 0)
{
// Some flag (A,B or both) is enabled
}
else
{
// None of them are...
Logic to test that 3 of 4 are True
I want to return True if and only if 3 out of 4 boolean values are true.
27 Answers
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What are the Ruby Gotchas a newbie should be warned about? [closed]
... while (not(expression)); in C/C++/...), actually never runs the statement if the expression is already true. This is because statement until expression is actually syntactic sugar over
until expression
statement
end
, the equivalent of which in C/C++ is while (not(expression)) statement; just ...
Shorten string without cutting words in JavaScript
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If I understand correctly, you want to shorten a string to a certain length (e.g. shorten "The quick brown fox jumps over the lazy dog" to, say, 6 characters without cutting off any word).
If this is the case, you can try so...
What does `kill -0 $pid` in a shell script do?
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sending the signal 0 to a given PID just checks if any process with the given PID is running and you have the permission to send a signal to it.
For more information see the following manpages:
kill(1)
$ man 1 kill
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If sig is 0, then no signal is sent, but error chec...
Foreach loop, determine which is the last iteration of the loop
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If you just need to do something with the last element (as opposed to something different with the last element then using LINQ will help here:
Item last = Model.Results.Last();
// do something with last
If you need to do ...
do..end vs curly braces for blocks in Ruby
...-line blocks and curly braces for single line blocks, but there is also a difference between the two that can be illustrated with this example:
puts [1,2,3].map{ |k| k+1 }
2
3
4
=> nil
puts [1,2,3].map do |k| k+1; end
#<Enumerator:0x0000010a06d140>
=> nil
This means that {} has a high...
How do I detect what .NET Framework versions and service packs are installed?
A similar question was asked here , but it was specific to .NET 3.5. Specifically, I'm looking for the following:
13 Answe...
How to sort an array of objects with jquery or javascript [duplicate]
...cts from the array
// thus a[1] and b[1] will equal the names
// if they are equal, return 0 (no sorting)
if (a[1] == b[1]) { return 0; }
if (a[1] > b[1])
{
// if a should come after b, return 1
return 1;
}
else
{
// if b should come after...