This preview shows page 1. Sign up to view the full content.
Unformatted text preview: nx445ctn. /s/i6/rno
iu/../redo urlb4ct. If you e ncounte r e rror w ith "ld: /usr/lib/gcc/x 86_64-re dha t-linux /4.4.5/crtbe gin.o: No such file : No such file or
Change 4.4.5 in above ins truc tion into 4.4.7.
Unfortunately , y ou need a lot of ex tra arguments to get "ld" to work on the EW S mac hines . You c an als o jus t invok e "gc c " and have
it do the above c all to "ld" for y ou:
gc- hlowrd- chlowrdo
c o el-ol l
The important part of this is "-l c " whic h means "link with the s tandard C library ". This library provides the implementation for the
"puts " func tion, s o we link with it to pac k age every thing we need in our ex ec utable. Step 5: Load
The "ldd" utility tells y ou what libraries an ex ec utable will load into memory when it's run. Run the above c ommand. Do y ou
rec ogniz e one of the libraries ? Step 6: Execute
Ok ay s o after all that, go ahead and run the program y ou produc ed:
This will load the program into memory and run it. You now have c reated a program that y ou c an run jus t lik e any other Unix program, c ongratulations !
W hy the ./ ?
Rec all that the Unix c ommand c onventions is :
program [arg1] ...
W hile the program c an be a path (c ontaining s las hes ), it c an als o jus t be the name of a program (no s las hes ) to mak e a
c ommand line us er's life eas ier. W hen y ou jus t s pec ify a name, the operating s y s tem s earc hes through s tandard loc ations
for binaries (s uc h as /us r/bin ) to find the program with that name. By default, mos t Unix s y s tems will not s earc h the
c urrent work ing direc tory (whic h is generally a good thing, bec aus e y ou don't want to be ac c identally ex ec uting s omething
y ou happen to be in the direc tory of). So y ou need to provide a path (s omething with s las hes ) to ex ec ute a program not in
the s tandard loc ations . Adding ./ is us ually the eas ies t way to do this . If y ou move to the parent direc tory , this would als o
hw3/hello-world T he r ecommended way to do it
Now that y ou k now the bas ic s teps of the building proc es s , we c an...
View Full Document
This document was uploaded on 03/22/2014.
- Fall '14