Брайан Керниган - UNIX — универсальная среда программирования

for (i = 1; i < argc-1; i++)

sv(argv[i], dir);

exit(0);

}

sv(file, dir) /* save file in dir */

char *file, *dir;

{

struct stat sti, sto;

int fin, fout, n;

char target[BUFSIZ], buf[BUFSIZ], *index();

sprintf(target, "%s/%s", dir, file);

if (index(file, '/') != NULL) /* strchr() in some systems */

error("won't handle '/'s in %s", file);

if (stat(file, &sti) == -1)

error("can't stat %s", file);

if (stat(target, &sto) == -1) /* target not present */

sto.st_mtime = 0; /* so make it look old */

if (sti.st_mtime < sto.st_mtime) /* target is newer */

fprintf(stderr, "%s: %s not copied\n", progname, file);

else if ((fin = open(file, 0)) == -1)

error("can't open file %s", file);

else if ((fout = creat(target, sti.st_mode)) == -1)

error("can't create %s", target);

while ((n = read(fin, buf, sizeof buf)) > 0)

if (write(fout, buf, n) != n)

error("error writing %s", target);

close(fin);

close(fout);

}

#include "error.c"

#include

system(s) /* run command line s */

char *s;

{

int status, pid, w, tty;

int (*istat)(), (*qstat)();

...

if ((pid = fork()) == 0) {

...

execlp("sh", "sh", "-c", s, (char*)0);

exit(127);

}

...

istat = signal(SIGINT, SIG_IGN);

qstat = signal(SIGQUIT, SIG_IGN);

while ((w = wait(&status)) != pid && w != -1)

;

if (w == -1)

status = -1;

signal(SIGINT, istat);

signal(SIGQUIT, qstat);

return status;

}

/*

* Safer version of system for interactive programs

*/

#include

#include

system(s) /* run command line s */

char *s;

{

int status, pid, w, tty;

int (*istat)(), (*qstat)();

extern char *progname;

fflush(stdout);

tty = open("/dev/tty", 2);

if (tty == -1) {

fprintf (stderr, "%s: can't open /dev/tty\n", progname);

return -1;

}

if ((pid = fork()) == 0) {

close(0);

dup(tty);

close(1);

dup(tty);

close(2);

dup(tty);

close(tty);

execlp("sh", "sh", "-c", s, (char*)0);

exit(127);

}

close(tty);

istat = signal(SIGINT, SIG_IGN);

qstat = signal(SIGQUIT, SIG_IGN);

while ((w = wait(&status)) != pid && w != -1)

;

if (w == -1)

status = -1;

signal(SIGINT, istat);

signal(SIGQUIT, qstat);

return status;

}

/* timeout: set time limit on a process */

#include

#include

int pid; /* child process id */

char *progname;

main(argc, argv)

int argc;

char *argv[];

{

int sec = 10, status, onalarm();

progname = argv[0];

if (argc > 1 && argv[1][0] == '-') {

sec = atoi(&argv[1][1]);

argc--;

argv++;

}

if (argc < 2)

error("Usage: %s [-10] command", progname);

if ((pid=fork()) == 0) {

execvp(argv[1], &argv[1]);

error("couldn't start %s", argv[1]);

}

signal(SIGALRM, onalarm);

alarm(sec);

if (wait(&status) == -1 || (status & 0177) != 0)

error("%s killed", argv[1]);

exit((status >> 8) & 0377);

}

onalarm() /* kill child when alarm arrives */

{

kill(pid, SIGKILL);

}

#include "error.c"

length($0) > 72 { print "Line", NR, "too long:", substr($0,1,60) }

ttyin() /* process response from /dev/tty (version 1) */

{

char buf[BUFSIZ];

FILE *efopen();

static FILE *tty = NULL;

if (tty == NULL)

tty = efopen("/dev/tty", "r");

if (fgets(buf, BUFSIZ, tty) == NULL || buf[0] == 'q')

exit(0);

else /* ordinary line */

return buf[0];

}

ttyin() /* process response from /dev/tty (version 2) */

{

char buf[BUFSIZ];

FILE *efopen();

static FILE *tty = NULL;

if (tty == NULL)

tty = efopen("/dev/tty", "r");

for (;;) {

if (fgets(buf,BUFSIZ,tty) == NULL || buf[0] == 'q')

exit(0);

else if (buf[0] == '!') {

system(buf+1); /* BUG here */

printf("!\n");

}

else /* ordinary line */

return buf[0];

}

}

#include "system.c"

/* vis: make funny characters visible (version 1) */

#include

#include

main() {

int c;

while ((c = getchar()) != EOF)

if (isascii(c) &&

(isprint(c) || c=='\n' || c=='\t' || c==' '))

putchar(c);

else

printf("\\%03o", c);

exit(0);

}

/* vis: make funny characters visible (version 2) */

#include

#include

main(argc, argv)

int argc;

char *argv[];

{

int с, strip = 0;

if (argc > 1 && strcmp(argv[1] , "-s") == 0)

strip = 1;

while ((c = getchar()) != EOF) if (isascii(c) &&

(isprint(c) || c=='\n' || c=='\t' || c==' '))

putchar(c);

else if (!strip)

printf("\\%03o", c);

exit(0);

}

/* vis: make funny characters visible (version 3) */

#include

#include

int strip = 0; /* 1 => discard special characters */

main(argc, argv)

int argc;

char *argv[];

{

int i;

FILE *fp;

while (argc > 1 && argv[1][0] == '-') {

switch (argv[1][1]) {

case 's': /* -s: strip funny chars */

strip = 1;

break;

default:

fprintf(stderr, "%s: unknown arg %s\n",

argv[0], argv[1]);

exit(1);

}

argc--;

argv++;

}

if (argc == 1)

vis(stdin);

for (i = 1; i < argc; i++)

if ((fp=fopen(argv[i], "r")) == NULL) {

fprintf(stderr, "%s: can't open %s\n",

argv[0], argv[i]);

exit(1);

} else {

vis(fp);

fclose(fp);

}

exit(0);

}

vis(fp) /* make chars visible in FILE *fp */

FILE *fp;

{

int c;

while ((c = getc(fp)) != EOF)

if (isascii(c) &&

(isprint(c) || c=='\n' || c=='\t' || c==' '))

putchar(c);

else if (!strip)

printf("\\%03o", с);

}

/* waitfile: wait until file stops changing */

#include

#include

#include

char *progname;

main(argc, argv)

int argc;

char *argv[];

{

int fd;

struct stat stbuf;

time_t old_time = 0;

progname = argv[0];

if (argc < 2)

error("Usage: %s filename [cmd]", progname);

if ((fd = open(argv[1], 0)) == -1)

error("can't open %s", argv[1]);

fstat(fd, &stbuf);

while (stbuf.st_mtime != old_time) {

old_time = stbuf.st_mtime;

sleep(60);

fstat(fd, &stbuf);

}

if (argc == 2) { /* copy file */

execlp("cat", "cat", argv[1], (char*)0);

error("can't execute cat %s", argv[1]);

} else { /* run process */

execvp(argv[2], &argv[2]);

error("can't execute %s", argv[2]);

}

exit(0);

}

#include "error.c"

# watchfor: watch for someone to log in

PATH=/bin:/usr/bin

case $# in

0) echo 'Usage: watchfor person' 1>&2; exit 1

esac

until who | egrep "$1"

do

sleep 60

done

# watchwho: watch who logs in and out

PATH=/bin:/usr/bin

new=/tmp/wwho1.$$

old=/tmp/wwho2.$$

> $old # create an empty file

while : # loop forever

do

who >$new

diff $old $new

mv $new $old