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Check Whether a User Exists
...n also check user by id command.
id -u name gives you the id of that user.
if the user doesn't exist, you got command return value ($?)1
And as other answers pointed out: if all you want is just to check if the user exists, use if with id directly, as if already checks for the exit code. There's no ...
LISTAGG in Oracle to return distinct values
... the_column)
from (
select distinct the_column
from the_table
) t
If you need more columns, something like this might be what you are looking for:
select col1, listagg(col2, ',') within group (order by col2)
from (
select col1,
col2,
row_number() over (partition by col...
Priority queue in .Net [closed]
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@DanBerindei: not necessary work if you need make running calculation (delete old items), heap only support deleting min or max
– Svisstack
Jul 27 '14 at 12:09
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Determine installed PowerShell version
...etermine what version of PowerShell is installed on a computer, and indeed if it is installed at all?
19 Answers
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Concatenate a vector of strings/character
If I have a vector of type character, how can I concatenate the values into string? Here's how I would do it with paste() :
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Check if instance is of a type
Using this to check if c is an instance of TForm .
9 Answers
9
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How can I check the system version of Android?
...ON.
CODENAME: The current development codename, or the string "REL" if this is a release build.
INCREMENTAL: The internal value used by the underlying source control to represent this build.
RELEASE: The user-visible version string.
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How to print third column to last column?
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Note that this only works if the delimiter is exactly the same between all columns... For example, you can't use cut with a delimiter like \d+. (That I know of.)
– Zach Wily
Jan 13 '10 at 21:11
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How to properly check if std::function is empty in C++11?
I was wondering how to properly check if an std::function is empty. Consider this example:
3 Answers
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Read a file line by line assigning the value to a variable
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The following reads a file passed as an argument line by line:
while IFS= read -r line; do
echo "Text read from file: $line"
done < my_filename.txt
This is the standard form for reading lines from a file in a loop. Explanation:
IFS= (or IFS='') prevents leading/trailing whitespace f...