리눅스 grep find의 매개변수에 대한 문제

$ echo "$0 $1 $2"
/bin/bash
$ alias fih='find /usr/include -type f -name \*.h | xargs grep --color=auto -Hn $0'
$ set -x
$ fih getpwent
+ xargs grep --color=auto -Hn /bin/bash getpwent
+ find /usr/include -type f -name '*.h'
grep: getpwent: No such file or directory
$ set +x
+ set +x
$ alias fih='find /usr/include -type f -name \*.h | xargs grep --color=auto -Hn $1'
$ set -x
$ fih getpwent
+ xargs grep --color=auto -Hn getpwent
+ find /usr/include -type f -name '*.h'
/usr/include/python2.7/pyconfig.h:329:/* Define to 1 if you have the `getpwent' function. */
/usr/include/pwd.h:85:extern struct passwd *getpwent (void);
/usr/include/pwd.h:95:extern struct passwd *fgetpwent (FILE *__stream);
/usr/include/pwd.h:129:   PLEASE NOTE: the `getpwent_r' function is not (yet) standardized.
/usr/include/pwd.h:140:extern int getpwent_r (struct passwd *__restrict __resultbuf,
/usr/include/pwd.h:164:extern int fgetpwent_r (FILE *__restrict __stream,

$ alias fff='find . -type f -name \*.c -o -name \*.h | xargs perl -pi -e'
$ fff 's/include/INCLUDE/g'
$ head src/main.c
#INCLUDE <stdio.h>
#INCLUDE <stdlib.h>
#INCLUDE <string.h>
...

$ unalias fff
$ function fff() { find . -type f -name \*.c -o -name \*.h | xargs perl -pi -e "s/$1/$2/g"; }
$ fff INCLUDE include
$ head src/main.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
...