These are shell programming commands - be very careful about the quotes:

Double quote --> " (?123 key then c)

Back quote --> ` (?123 key then ALT key then 2)

You pasted the command correctly in this post but apparently not in the command terminal. There are non-breaking double quote-back quote or back quote-double quote sequences. And there's no dot between getprop and haret.kernel as well.

Also remember to unplug USB before trying.

Assuming that, in terminal, quotes are obtained in these way:

' typing [?123 then c]

" typing [?123 then x]

` typing [?123 then ALT then 2]

I tryed:

1)kexec --command-line=''cat /proc/cmdline'' -l ''getprop haret.kernel''

kexec --command-line=[?123 then c][?123 then c]cat /proc/cmdline[?123 then c][?123 then c] -l [?123 then c][?123 then c]getprop haret.kernel[?123 then c][?123 then c]

Result:

It seems to work, no error on terminal.

But when i use the successive commands synk[enter] kexec -e[enter], system hangs (I need to remove battery)

2)kexec --command-line="cat /proc/cmdline" -l "getprop haret.kernel"

kexec --command-line=[?123 then x]cat /proc/cmdline[?123 then x] -l [?123 then x]getprop haret.kernel[?123 then x]

Result:

Cannot open `getprop haret.kernel': No such file or directory

3)kexec --command-line="`cat /proc/cmdline`" -l "`getprop haret.kernel`"

kexec --command-line=[?123 then x][?123 then ALT then 2]cat /proc/cmdline[?123 then ALT then 2][?123 then x] -l [?123 then x][?123 then ALT then 2]getprop haret.kernel[?123 then ALT then 2][?123 then x]

Result:

Cannot open `': No such file or directory

4)kexec --command-line=''`cat /proc/cmdline`'' -l ''`getprop haret.kernel`''

kexec --command-line=[?123 then c][?123 then c][?123 then ALT then 2]cat /proc/cmdline[?123 then ALT then 2][?123 then c][?123 then c] -l [?123 then c][?123 then c][?123 then ALT then 2]getprop haret.kernel[?123 then ALT then 2][?123 then c][?123 then c]

Result:

Cannot open `root=/dev/mmcblk1p2': No such file or directory

(root=/dev/mmcblk1p2 is the partition written into my startup.txt)

Thanks.