[BONE]Why canNOT edit LED's trigger file with vi ?

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1

Hi all
I see the LED's trigger file is a text file:
$ file trigger
trigger: ASCII text

But why can not edit it with vi?
Why must do "echo none > trigger "?

A normal flat text file with operation "echo none > file",
we should get the string "none" in it.
But why I get "
[none] mmc0 timer heartbeat backlight gpio default-on
"
in it ?

Thank you.

Roka

2

I believe the reason you can’t edit the file with VI is because its a streaming file (wich is protected).

I dont know for sure but you should add quotations around none in order to cast it into the file properly (echo “none” > trigger)

3

I guess your are talking about sysfs file.
These are something like sockets: you can write (echo) and read (cat) from those but you cannot seek through them (edit). They are here to provide easy and practical access to system settings.

4

Technically, you can read from the file and seek to the beginning to
read again without closing/opening.

But indeed that's not sufficient for normal editors...

5

Hello
I did "ls -l " to see the attribution of the file .
$ ls -l
-rw-r--r-- 1 root root 4096 Feb 14 15:15 trigger
$ file trigger
trigger: ASCII text

But it gave me the normal file attribution by the 1st byte.
I want to know how this OS dealing this.

Best.

Roka