Cat magic - end of input
When "cat> xx.txt <EOF" is entered on the command line, further input from cmdline goes into the xx.txt file until EOF is written. EOF is not a sacred word here, if the command was instead cat> xx.txt <<BBB then the cmdline input goes to xx.txt until BBB is written. I don't know what is the reason (<end_of_input_sequence). The Cat man page explains little. I've only seen this in scripts, etc.
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This is a feature of the shell, not cat
- so you won't find it in the manual cat
.
It is known as the "Here" document - see this Advanced Bash-Scripting Guide page for any documentation.
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This syntax is called Here Document (scroll a little to find it).
This does not apply to any team, not a cat more than any other team; and it can be found in the shell man; for example man bash
:
3.6.6 Here Documents
This type of redirection instructs the shell to read input from the current source as long as a line containing only a word (no trailing spaces) has been seen. All lines are read up to this point then used as the standard input for the command.
(Not a complete quote - there is more to read in a person)
BTW, this is a syntax that has been reused in some programming languages like PHP; -)
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