??????  ?????

1 : #!/usr/local/bin/perl
2 :
3 : open (WOUT, "w|");
4 : $time = <WOUT>;
5 : $time =~ s/^ *//;
6 : $time =~ s/ .*//;
7 : ; # skip headings line
8 : @users = ;
9 : close (WOUT);
10: foreach $user (@users) {
11:   $user =~ s/ .*//;
12: }
13: print ("Current time: $time");
14: print ("Users logged on:\n");
15: $prevuser = "";
16: foreach $user (sort @users) {
17:   if ($user ne $prevuser) {
18:     print ("\t$user");
19:     $prevuser = $user;
20:   }
21: }

Current time: 4:25pm
Users logged on:
  dave
  kilroy
  root
  zarquon

  4:25pm  up 1 day,  6:37,  6 users,  load average: 0.79, 0.36, 0.28
User     tty       login@  idle   JCPU   PCPU what
dave     ttyp0     2:26pm           27      3 w
kilroy   ttyp1     9:01am  2:27   1:04     11 -csh
kilroy   ttyp2     9:02am    43   1:46     27 rn
root     ttyp3     4:22pm     2               -csh
zarquon  ttyp4     1:26pm     4     43     16 cc myprog.c
kilroy   ttyp5     9:03am         2:14     48 /usr/games/hack

1: #!/usr/local/bin/perl
2:
3: open (STDOUT, ">file1") || die ("open STDOUT failed");
4: open (STDERR, ">&STDOUT") || die ("open STDERR failed");
5: print STDOUT ("line 1\n");
6: print STDERR ("line 2\n");
7: close (STDOUT);
8: close (STDERR);

1 : #!/usr/local/bin/perl
2 :
3 : open (STDOUT, ">file1") || die ("open STDOUT failed");
4 : open (STDERR, ">&STDOUT") || die ("open STDERR failed");
5 : $| = 1;
6 : select (STDERR);
7 : $| = 1;
8 : print STDOUT ("line 1\n");
9 : print STDERR ("line 2\n");
10: close (STDOUT);
11: close (STDERR);

1: #!/usr/local/bin/perl
2:
3: while ($line = <>) {
4:   print ($line);
5:   if (eof) {
6:     print ("-- end of current file --\n");
7:   }
8: }

$ program file1 file2
This is a line from the first file.
Here is the last line of the first file.
-- end of current file --
This is a line from the second and last file.
Here is the last line of the last file.
-- end of current file --
$

1: #!/usr/local/bin/perl
2:
3: while ($line = <>) {
4:   print ($line);
5:   if (eof()) {
6:     print ("-- end of output --\n");
7:   }
8: }

$ program file1 file2
This is a line from the first file.
Here is the last line of the first file.
This is a line from the second and last file.
Here is the last line of the last file.
-- end of output --$

1: #!/usr/local/bin/perl
2:
3: &open_file("INFILE", "", "file1");
4: &open_file("OUTFILE", ">", "file2");
5: while ($line = &read_from_file("INFILE")) {
6:   &print_to_file("OUTFILE", $line);
7: }
8:
9: sub open_file {
10:   local ($filevar, $filemode, $filename) = @_;
11:
12:   open ($filevar, $filemode . $filename) ||
13:     die ("Can't open $filename");
14: }
15: sub read_from_file {
16:   local ($filevar) = @_;
17:
18:   <$filevar>;
19: }
20: sub print_to_file {
21:   local ($filevar, $line) = @_;
22:
23:   print $filevar ($line);
24: }

??????	seek
??????	seek (filevar, distance, relative_to);
???	??????????/??????????????????? 1??filevar????????? 2??distance????????????????????????????????????? 3??reletive_to??????0??1??2???0??????????????????1??????????λ??????????????У???????2????????????β????? ???г???????棨??????????????????????tell???????á?

??????	tell
??????	tell (filevar);
???	??????????????λ?????? ??? 1??seek??tell???????????????????????? 2??seek??tell???????????????????????

??????	read
??????	read (filevar, result, length, skipval);
???	read??????????UNIX??fread??????Ч??????????????????????????????????????????????????? 1??filevar????????? 2??result???????????????????????????? 3??length???????????? 4??skipval?????????????????????????????? ????????????????????????????????β????????????????????????

??????	sysread
??????	sysread (filevar, result, length, skipval);
???	??????????????UNIX????read??Ч????????read?????

??????	syswrite
??????	syswrite (filevar, data, length, skipval);
???	?????д?????????UNIX????write??Ч???????? 1??filevar?????д?????? 2??data???????д?????????? 3??length???д???????? 4??skipvalд???????????????????

??????	getc
??????	$char = getc (infile);
???	??????ж???????????

??????	binmode
??????	binmode (filevar);
???	?????????????DOS?????????????????????????????????á??????????????????????á?

??????	rename
??????	rename (oldname, newname);
???	???????????????????????У????????????????????

??????	unlink
??????	num = unlink (filelist);
???	???????????????????б???????????????????????? ???????????unlink??????delete???????????????????????????????

??????	link
??????	link (newlink, file);
???	?????????????????--??????file?????????????newlink?????????????? ????????棬???????? ????????????????е????????????????????????????????

??????	symlink
??????	symlink (newlink, file);
???	???????????????????????????????????????????????????????????????? ??????????????磺??unlinke??????????????????????????????????????????????????????????????

??????	readlink
??????	filename = readlink (linkname);
???	???linkname??????????????????????????????????????????

??????	chmod
??????	chmod (permissions, filelist);
???	?????????????????????? 1??permissions??????????????京???????mkdir?????? 2??filelist??????????????б?

??????	chown
??????	chown (userid, groupid, filelist);
???	?????????????????????????? 1??userid??????????(????)ID?? 2??groupid???μ???(????)ID???-1???????? 3??filelist?????????????????б?

??????	umask
??????	oldmaskval = umask (maskval);
???	???????????????????????????????

??????	truncate
??????	truncate (filename, length);
???	??????????????length?????????????????С??length???????κ????????filename?????????????????????????

??????	stat
??????	stat (file);
???	??????????????file??????????????????????????б??????????? ????????豸 ????ο???(inode) ??????? ??????? ??????(????)ID ???????(????)ID ?豸????????file???豸????? ?????С????????? ????????? ????????? ?????????? I/O?????????С ???????????????

??????	lstat
??????	lstat (file);
???	??stat????????????file??????????????

??????	time
??????	currtime = time();
???	?????1970??1??1?????????????

??????	gmtime
??????	timelist = gmtime (timeval);
???	????time, stat ?? -A ?? -M ????????????????????????????????????????б??????????? ?? ???? С???0~23 ???? ?·??0~11(???~?????) ??? ?????0~6(????~????) ????е??????0~364 ???????????? ???UNIX??gmtime??????

??????	localtime
??????	timelist = localtime (timeval);
???	??gmtime???????????????????????????

??????	utime
??????	utime (acctime, modtime, filelist);
???	??????????????????????????????磺 $acctime = -A "file1"; $modtime = -M "file1"; @filelist = ("file2", "file3"); utime ($acctime, $modtime, @filelist);

??????	fileno
??????	filedesc = fileno (filevar);
???	????????????UNIX?????????????filevar??????????

??????	fcntl flock
??????	fcntl (filevar, fcntlrtn, value); flock (filevar, flockop);
???	??????UNIX??????????

??????	dbmopen
??????	dbmopen (array, dbmfilename, permissions);
???	????????????DBM????????????????? 1??array?????ù??????? 2??dbmfilename????????DBM????? 3?????????????mkdir

??????	dbmclose
??????	dbmclose (array);
???	???DBM?????????????????????????

????? ????? ??