Hi Bill, > command.c: In function 'c_interp': > command.c:55: error: invalid lvalue in assignment You have an invalid lvalue in your assignment on-or-near line 55. > command.c: In function 'c_condition': > command.c:190: error: invalid lvalue in assignment > command.c:194: error: invalid lvalue in assignment You have two more invalid lvalue in your assignments on-or-near lines 190 and 194. > command.c: In function 'c_doall': > command.c:215: warning: incompatible implicit declaration of built-in function 'strlen' It appears you forgot to #include <string.h> at the top of your command.c file. Or your source re-declares strlen in an incompatible way. HTH, --Eljay