Editing text from command line

What would be the Linux command to write and save certain text string to a file?

That depends. If all you want to do is write a line of text to a file you could do this:

Code:

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echo Some text you want > targetfilename.txt

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If instead you want a full-blown text editor, there are a few choices (some easier to pick up than others):

vi
emacs
nano
pico
joe
jpico