[PerlChina] Re: 16进制文件操作

谢谢
perldoc -f seek的结论貌似跟这个不一样 ？

seek FILEHANDLE,POSITION,WHENCE
Sets FILEHANDLE's position, just like the "fseek" call of
"stdio". FILEHANDLE may be an expression whose value gives
the
name of the filehandle. The values for WHENCE are 0 to set
the
new position *in bytes* to POSITION, 1 to set it to the
current
position plus POSITION, and 2 to set it to EOF plus POSITION
(typically negative). For WHENCE you may use the constants
"SEEK_SET", "SEEK_CUR", and "SEEK_END" (start of the file,
current position, end of the file) from the Fcntl module.
Returns 1 upon success, 0 otherwise.

Note the *in bytes*: even if the filehandle has been set to
operate on characters (for example by using the ":utf8" open
layer), tell() will return byte offsets, not character
offsets
(because implementing that would render seek() and tell()
rather
slow).

If you want to position file for "sysread" or "syswrite",
don't
use "seek"--buffering makes its effect on the file's system
position unpredictable and non-portable. Use "sysseek"
instead.

Due to the rules and rigors of ANSI C, on some systems you
have
to do a seek whenever you switch between reading and
writing.
Amongst other things, this may have the effect of calling
stdio's clearerr(3). A WHENCE of 1 ("SEEK_CUR") is useful
for
not moving the file position:

seek(TEST,0,1);

This is also useful for applications emulating "tail -f".
Once
you hit EOF on your read, and then sleep for a while, you
might
have to stick in a seek() to reset things. The "seek"
doesn't
change the current position, but it *does* clear the end-of-
file
condition on the handle, so that the next "<FILE>" makes
Perl
try again to read something. We hope.

If that doesn't work (some IO implementations are
particularly
cantankerous), then you may need something more like this:

for (;;) {
for ($curpos = tell(FILE); $_ = <FILE>;
$curpos = tell(FILE)) {
# search for some stuff and put it into files
}
sleep($for_a_while);
seek(FILE, $curpos, 0);
}

另外，您的code 我尝试了一下
seek ($fp, 0, 0x80);
print $fp "\x0";
实际的效果是 00000000h这一行 第1和2字节变成了0 没有偏移？
我自己尝试
seek ($fp, 16*8, 0x00);
print $fp "\x0";
可以达到目的

另外 我想请教 如何删除掉一部分内容呢 比如 0x90-0xb0
谢谢
On 8月8日, 上午12时48分, Anthony WU <anthonywu...@gmail.com> wrote:
> 以你所說的操作大約是
> open (my $fp, '+<', 'x.dat');
> binmode ($fp);
> seek ($fp, 0, 0x80);
> print $fp "\x0";
> seek ($fp, 0, 0x82);
> print $fp "\x0";
> seek ($fp, 0, 0x84);
> print $fp "\x0";
> seek ($fp, 0, 0x86);
> print $fp "\x8B";
> seek ($fp, 0, 0x87);
> print $fp "\x8B";
> seek ($fp, 0, 0x88);
> print $fp "\x0A";
> seek ($fp, 0, 0x89);
> print $fp "\x0A";
> ....
> ....
> ....
> close ($fp);
>
>
>
> -------- Original Message --------
> Subject: [PerlChina] Re: 16进制文件操作
> From: perlw01f <p3r1w...@gmail.com>
> To: PerlChina Mongers 讨论组 <perlchina@googlegroups.com>
> Date: 7/8/2009 21:16
> > 都是在确定的位置
>
> > 如 00000080h 这一栏 第1 3 5 字节换为0 78换为8B 9 10 换为0A 还有一些其他的
>
> > On 8月7日, 下午9时04分, Anthony WU <anthonywu...@gmail.com> wrote:
>
> >> 你的字節是定位修改的嗎？有什麼規律的？
>
> >> -------- Original Message --------
> >> Subject: [PerlChina] Re: 16进制文件操作
> >> From: perlw01f <p3r1w...@gmail.com>
> >> To: PerlChina Mongers 讨论组 <perlchina@googlegroups.com>
> >> Date: 7/8/2009 20:56
>
> >>> 我有一个文件 x.dat，由x.rar.gz压缩而成 但是其中某些字节做了修改处理 现在的文件名是 a.dat
> >>> 现在 我想逆行操作，即
> >>> 先将a.date rename成x.rar.gz 然后利用ue修改某些字节 之后才能解压缩成x.date
>
> >>> 由于文件数量较多 且ue 16进制 修改也不是很方便
> >>> 所以想 用 perl实现
> >>> 谢谢
>
> >>> On 8月7日, 下午5时17分, cnhack TNT <cnhack...@gmail.com> wrote:
>
> >>>> 能举例说明你要做的事情么？
>
> >>>> 2009/8/7 perlw01f <p3r1w...@gmail.com>
>
> >>>>> perl中 有没有类似ultredit中那种直接转换成16进制进行操作的方法或者module
>
> >>>>> unpack是不是太费事了
>
> >> --
> >> Best Regards,
> >> Anthony WU
>
> --
> Best Regards,
> Anthony WU
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