Writing C program to implement UNIX commands like grep.

Writing C program to implement UNIX commands like grep.

Code:

#include<stdio.h> #include<unistd.h> #include<stdlib.h> #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include<string.h> #include <fcntl.h> void match_pattern(char *argv[]) { int fd,r,j=0; char temp,line[100]; if((fd=open(argv[2],O_RDONLY)) != -1) { while((r=read(fd,&temp,sizeof(char)))!= 0) { if(temp!='\n') { line[j]=temp; j++; } else { if(strstr(line,argv[1])!=NULL) printf("%s\n",line); memset(line,0,sizeof(line)); j=0; } } } } main(int argc,char *argv[]) { struct stat stt; if(argc==3) { if(stat(argv[2],&stt)==0) match_pattern(argv); else { perror("stat()"); exit(1); } } }

Output:

elcot@elcot:~$ gcc -o g1 grepc.c
elcot@elcot:~$ ./g1 hai test1
hai how are you

Hints:

elcot@elcot:~$ gcc -o g1 grepc.c  ->Compile
grepc.c ->program name
g1 -> create object

elcot@elcot:~$ ./g1 hai test1  -> Run
g1 -> object
hai -> string
test1 -> file name

This is grep command implementation.
grep syntax:
grep <String> <file name>

grep command is used to search a  particular word in file.etc.