Task 4: Input/Output Redirection Your shell must support I/O redirection. If an external command is followed by , your shell must arrange it so

Task 4: Input/Output Redirection Your shell must support I/O redirection. If an external command is followed by "<", it must read input from the named file. For example, the command line "sort < foo" means that sort should be fed the file foo via stdin. If an external command is followed by a ">", your shell must arrange it so that stdout of the command is directed to a file. For example, "ls > save" means that the ls command should save its output to the file named "save". You could have both on the same command, for example: "sort < infile > outfile".

#include #include #include #include #include #include #include /* Simple example of using gnu readline to get lines of input from a user. Needs to be linked with -lreadline -lcurses add_history tells the readline library to add the line to it's internal history, so that using up-arrow (or ^p) will allows the user to see/edit previous lines. */ int main(int argc, char **argv) { char *s;

while (s=readline("prompt> ")) { add_history(s); /* adds the line to the readline history buffer */

if((strcmp(s,"pwd"))==0)//Check if input is pwd { char* cwd; char buff[PATH_MAX + 1]; cwd = getcwd( buff, PATH_MAX + 1 ); printf( "Directory is %s. ", cwd );//Print the directory if input is pwd }

else if((strcmp(s,"exit"))==0)//Check if input is exit { exit(0);//Exit } else if(s[0]='c'&& s[1]=='d')//Check if first two letters of input is c and d {

char a[50],b[3]; sscanf(s,"%s %s",b,a);//Scanf the directory in a chdir(a);//Change directory to a } free(s); /* clean up! */ } return(0);}