c - Use a variable in system() and store its output in a file -


i want store output of system() in file uses string variable. 

char file[10],command[100]; printf("enter file name:\n"); fgets(file,10,stdin); sprintf(command,"lsof | grep %s >> result.txt",file); system(command);

result.txt comes out empty.

after enter data 

fgets(file,10,stdin);

you press enter key. fgets includes newline character(\n) in buffer(file) unless input more 8 characters long.

to fix problem, need strip off newline character file problem-maker. can achieve using cool function strcspn() string.h. add following after fgets:

buffer[strcspn(buffer,"\n")] = 0;

or else, use familiar strlen() function:

size_t len = strlen(buffer);  if(len > 0 && buffer[len-1] == '\n')     buffer[len-1] = 0;

you should check if system() , fgets() successful checking return values.


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