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Appending a line to a file only if it does not already exist
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Just keep it simple :)
grep + echo should suffice:
grep -qxF 'include "/configs/projectname.conf"' foo.bar || echo 'include "/configs/projectname.conf"' >> foo.bar
-q be quiet
-x match the whole line
-F pattern is a plain string
https://linux.die.net/man/1/grep
Edit:
inco...
In PHP, can you instantiate an object and call a method on the same line?
... @CMCDragonkai logically that makes sense; the object only exists for the duration of the statement (new Foo)->property - the value you are storing has nowhere to go because the object will no longer exist after that as it's not stored anywhere.
– thomasrutter...
Test for non-zero length string in Bash: [ -n “$var” ] or [ “$var” ]
...ting the contents of the variable as if they were part of the conditional expression (the result matches the assertion implied by the "T" or "F" in the description column). When [[ is used (column 1b), the variable content is seen as a string and not evaluated.
The errors in columns 3a and 5a are c...
Parse JSON in C#
I'm trying to parse some JSON data from the Google AJAX Search API. I have this URL and I'd like to break it down so that the results are displayed. I've currently written this code, but I'm pretty lost in regards of what to do next, although there are a number of examples out there with simplifie...
How to do a non-greedy match in grep?
...ng for a non-greedy (or lazy) match. To get a non-greedy match in regular expressions you need to use the modifier ? after the quantifier. For example you can change .* to .*?.
By default grep doesn't support non-greedy modifiers, but you can use grep -P to use the Perl syntax.
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CSS: fixed position on x-axis but not y?
Is there a way to fix a position on the x-axis only? So when a user scrolls up, the div tag will scroll up with it, but not side to side?
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How to write a cron that will run a script every day at midnight?
...--0 minutes and 0 hours--and the *s mean every day of every month.)
Syntax:
mm hh dd mt wd command
mm minute 0-59
hh hour 0-23
dd day of month 1-31
mt month 1-12
wd day of week 0-7 (Sunday = 0 or 7)
command: what you want to run
all numeric values can be replaced by * which mean...
Fastest method to replace all instances of a character in a string [duplicate]
...g/character in a string in JavaScript? A while , a for -loop, a regular expression?
14 Answers
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How can a LEFT OUTER JOIN return more records than exist in the left table?
... was at least one record in the right table but thank you so much for the explanation.
– Jay Wilde
Sep 6 '18 at 17:43
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Using vagrant to run virtual machines with desktop environment
... development environment is based on virtual machines, running on VirtualBox. We would like to move one step further, and use the capabilities of Vagrant to have the description of the machine in a text file and then be able to "raise" that machine based on that text file. Combined to puppet, this w...