Answer to Quiz 12 Fri 20 Apr 2001

With the UNIX command grep we can search in a file for strings that match a given string. For example,
```
   prompt> grep name file
```
will display on screen all lines in file that contain the string name. The function void callgrep ( const char *string, const char *filename ) calls the grep command with as arguments the actual content of the variables string and filename. Give the implementation of callgrep below :
```
    void callgrep ( const char *string, const char *filename )
    {
       char *cmd;
 
       sprintf(cmd, "grep %s %s", string, filename);
       system(cmd);
    }
```

Consider the following makefile :

all: P1 P3
P1: P2
        @echo n
P2:
        @echo e
P3:
        @echo d

What is printed on screen when make is typed?

e
n
d