Брайан Керниган - UNIX — универсальная среда программирования

cat >$new # collect the input

cp $new $1 # overwrite the input file

rm -f $new

# overwrite: copy standard input to output after EOF

# version 2. BUG here too

PATH=/bin:/usr/bin

case $# in

1) ;;

*) echo 'Usage: overwrite file' 1>&2; exit 2

esac

new=/tmp/overwr1.$$

old=/tmp/overwr2.$$

trap 'rm -f $new $old; exit 1' 1 2 15

cat >$new # collect the input

cp $1 $old # save original file

trap '' 1 2 15 # we are committed; ignore signals

cp $new $1 # overwrite the input file

rm -f $new $old

# overwrite: copy standard input to output after EOF

# final version

opath=$PATH

PATH=/bin:/usr/bin

case $# in

0|1) echo 'Usage: overwrite file cmd [args]' 1>&2; exit 2

esac

file=$1; shift

new=/tmp/overwr1.$$; old=/tmp/overwr2.$$

trap 'rm -f $new $old; exit 1' 1 2 15 # clean up files

if PATH=$opath >$new # collect input

then

cp $file $old # save original file

trap '' 1 2 15 # we are committed; ignore signals

cp $new $file

else

echo "overwrite: $1 failed, $file unchanged" 1>&2

exit 1

fi

rm -f $new $old

/* p: print input in chunks (version 1) */

#include

#define PAGESIZE 22

char *progname; /* program name for error message */

main(argc, argv)

int argc;

char *argv[];

{

int i;

FILE *fp, *efopen();

progname = argv[0];

if (argc == 1)

print(stdin, PAGESIZE);

else

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

fp = efopen(argv[i], "r");

print(fp, PAGESIZE);

fclose(fp);

}

exit(0);

}

print(fp, pagesize) /* print fp in pagesize chunks */

FILE *fp;

int pagesize;

{

static int lines = 0; /* number of lines so far */

char buf[BUFSIZ];

while (fgets(buf, sizeof buf, fp) != NULL)

if (++lines < pagesize)

fputs(buf, stdout);

else {

buf[strlen(buf)-1] = '\0';

fputs(buf, stdout);

fflush(stdout);

ttyin();

lines = 0;

}

}

#include "ttyin1.c"

#include "efopen.c"

/* p: print input in chunks (version 2) */

#include

#define PAGESIZE 22

char *progname; /* program name for error message */

main(argc, argv)

int argc;

char *argv[];

{

FILE *fp, *efopen();

int i, pagesize = PAGESIZE;

progname = argv[0];

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

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

argc--;

argv++;

}

if (argc == 1)

print(stdin, pagesize);

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

fp = efopen(argv[i], "r");

print(fp, pagesize);

fclose(fp);

}

exit(0);

}

print(fp, pagesize) /* print fp in pagesize chunks */

FILE *fp;

int pagesize;

{

static int lines = 0; /* number of lines so far */

char buf[BUFSIZ];

while (fgets(buf, sizeof buf, fp) != NULL)

if (++lines < pagesize)

fputs(buf, stdout);

else {

buf[strlen(buf)-1] = '\0';

fputs(buf, stdout);

fflush(stdout);

ttyin();

lines = 0;

}

}

#include "ttyin2.c"

#include "efopen.c"

/* p: print input in chunks (version 3) */

#include

#define PAGESIZE 22

char *progname; /* program name for error message */

main(argc, argv)

int argc;

char *argv[];

{

FILE *fp, *efopen();

int i, pagesize = PAGESIZE;

char *p, *getenv();

progname = argv[0];

if ((p=getenv("PAGESIZE")) != NULL)

pagesize = atoi(p);

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

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

argc--;

argv++;

}

if (argc == 1)

print(stdin, pagesize);

else

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

fp = efopen(argv[i], "r");

print(fp, pagesize);

fclose(fp);

}

exit(0);

}

print(fp, pagesize) /* print fp in pagesize chunks */

FILE *fp;

int pagesize;

{

static int lines = 0; /* number of lines so far */

char buf[BUFSIZ];

while (fgets(buf, sizeof buf, fp) != NULL)

if (++lines < pagesize)

fputs(buf, stdout);

else {

buf[strlen(buf)-1] = '\0';

fputs(buf, stdout);

fflush(stdout);

ttyin();

lines = 0;

}

}

#include "ttyin2.c"

#include "efopen.c"

/* p: print input in chunks (version 4) */

#include

#define PAGESIZE 22

char *progname; /* program name for error message */

main(argc, argv)

int argc;

char *argv[];

{

FILE *fp, *efopen();

int i, pagesize = PAGESIZE;

char *p, *getenv(), buf[BUFSIZ];

progname = argv[0];

if ((p=getenv("PAGESIZE")) != NULL)

pagesize = atoi(p);

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

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

argc--;

argv++;

}

if (argc == 1)

print(stdin, pagesize);

else

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