This is due sysfs being pseudo filesystem, as procfs is as well.
It's actually an interface from kernel space to user space which allows you to manipulate various options regarding your hardware or operating system values.
Options such as fibre rescan, ip4 forwarding etc are all controlled by user using those pseudo file systems.
A lot of those options have real backed configuration files (such as /etc/sysctl.conf) which will apply those on boot.
That file system is created after system is booted (or on request) and populated with your device files.
For instance, if you add additional fibre card, a sysfs will be populated with additional hierarchy for that card.
An actual echo command is predetermined, if you issue anything else error will be written.
Take the following example from my PC at home :
root# echo "- - -" > /sys/class/scsi_host/host1/scan
root# tail -f /var/log/messages
kernel: [ 6598.240883] ata2: hard resetting link
kernel: [ 6598.555362] ata2: SATA link down (SStatus 0 SControl 300)
kernel: [ 6598.555382] ata2: EH complete
root# echo "gibberish" > /sys/class/scsi_host/host1/scan
-su: echo: write error: Invalid argument
Thank You very much Peasant.
Hi Leo
Will try cat those files when I reach home. If I remember correctly, i couldn't cat those files even as root.
file command's output from my above post says no read permission too.