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How to make “if not true condition”?
I would like to have the echo command executed when cat /etc/passwd | grep "sysa" is not true.
6 Answers
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How to test if a string is JSON or not?
I have a simple AJAX call, and the server will return either a JSON string with useful data or an error message string produced by the PHP function mysql_error() . How can I test whether this data is a JSON string or the error message.
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How is the default submit button on an HTML form determined?
...ing equivalent), then none of the submit buttons are considered successful and none of their values are included in the submitted data. (Note that if you submit the form by using submitElement.click() then the submit that you had a reference to is considered active; this doesn't really fall under t...
Rails 4 - passing variable to partial
I am following the Ruby on Rails tutorial and have come across a problem while trying to pass variables to partials.
7 Answ...
Rails Migration: Remove constraint
... postfix: "",
imageUploader: {
brandingHtml: "Powered by \u003ca href=\"https://imgur.com/\"\u003e\u003csvg class=\"svg-icon\" width=\"50\" height=\"18\" viewBox=\"0 0 50 18\" fill=\"none\" xmlns=\"http://www.w3.org/2000/svg\"\u003e\u003cpath d=\"M46.1709 9....
Insert a line at specific line number with sed or awk
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mac users: with homebrew, brew install gnu-sed and then use this with gsed
– cwd
Jan 10 '15 at 17:58
4
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How to upgrade all Python packages with pip?
...finite potential variations for this. I'm trying to keep this answer short and simple, but please do suggest variations in the comments!
In older version of pip, you can use this instead:
pip freeze --local | grep -v '^\-e' | cut -d = -f 1 | xargs -n1 pip install -U
The grep is to skip editable...
Benefit of using Parcelable instead of serializing object
As I understand, Bundle and Parcelable belongs to the way Android performs serialization in. It is used for example in passing data between activities. But I wonder, if there are any benefits in using Parcelable instead of classic serialization in case of saving state of my business objects to...
data.frame rows to a list
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Like this:
xy.list <- split(xy.df, seq(nrow(xy.df)))
And if you want the rownames of xy.df to be the names of the output list, you can do:
xy.list <- setNames(split(xy.df, seq(nrow(xy.df))), rownames(xy.df))
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How to drive C#, C++ or Java compiler to compute 1+2+3+…+1000 at compile time?
...ing compiler features. This means that I am not allowed to write a program and execute it, but I should just write a program that could drive the compiler to compute this sum while compilation and print the result when compilation completes. As a hint, he told me that I may use generics and pre-proc...