shell linux is it possible to treat variable assignation contained into a string?-CodePudding

I wonder if it’s possible in shell to use variable declared into a string ?
I dont know how to be explicit so here is my problem :

I use raspi-gpio for drive gpio, and i want to know states of one GPIO example :
raspi-gpio get 21

return a string :
GPIO 21: level=0 fsel=0 func=INPUT

Into this string there is level=0; fsel=0 and func=INPUT that are like variable declaration for shell.

My question :
Is it possible with minimum line to treat this 3 declarations as variable, for direct use :
if $level == 0 then...

CodePudding user response：

Assuming command raspi-gpio get 21 returns GPIO 21: level=0 fsel=0 func=INPUT

We can delete unneeded GPIO 21: in front by "splitting" it from colon (:) character.

Then pipe the output to next command to replace space with newline.

So we have this command:

GPIO_OUTPUT=`raspi-gpio get 21`
MYCMD=`echo $GPIO_OUTPUT | cut -d':' -f2 | tr ' ' '\n'`

output of echo -e "$MYCMD" would be:


level=0
fsel=0
func=INPUT

This already looks like a valid bash variable assignment, so we can just source it:

source <(echo -e $MYCMD)

Complete code:

GPIO_OUTPUT=`raspi-gpio get 21`
MYCMD=`echo $GPIO_OUTPUT | cut -d':' -f2 | tr ' ' '\n'`
source <(echo -e $MYCMD)
if [ $level -eq 0 ] ; then
  echo "level is zero"
fi