eval recorder

[AbRiahi]

Hi everybody

I want to know what is the difference between "eval recorder" and "recorder command" in OpenSees, e.g. in the following commands of SCBF example in Discovering Opensees?
What will happen if we omit eval from the second command?

recorder Element -xml "$dataDir/$subDir2/Column_Force.out" -time -ele 11 12 force
eval recorder Element -xml "$dataDir/$subDir2/Brace_MN_ForceDeformation.out" -time -ele $lst section 1 forceAndDeformation

[fmk]

it is just useful when you want to provide lists of values to a command as you have in the above:

e.g. if you create a list:
set eList 11 12 15 16 17 18 20 21
this works:
eval "recorder Element ..... -ele $eList force"
this won't:
recorder Eleemnt ... -ele $eList force"

e.g. -ele 11 12

[AbRiahi]

thank you very much