11-29-2010
Why should it? There are systems where "char" isn't 8 bits... Or were, decades ago, and the C standard people latch onto this technicality like a bear trap and refuse to let go.
It plainly doesn't assume it stops at 8 bits, anyway, so the question's kind of pointless.
10 More Discussions You Might Find Interesting
1. Programming
HI
Hi I have a character string which contains some special characters and I need it to display as a hex string.
For example, the sample i/p string: ×¥ïA Å gïÛý and
the o/p should be : D7A5EF4100C5010067EFDBFD
Any pointers or sample code pls. (5 Replies)
Discussion started by: axes
5 Replies
2. Shell Programming and Scripting
Hi,
what is the escape char for " in shell script. following way i want to write file using echo command
echo "LOAD DATA
infile '&1'
APPEND
INTO TABLE dummy_table
FIELDS TERMINATED BY ','
OPTIONALLY ENCLOSED BY '"' - single quote and double quote and single quote - gives error here... (1 Reply)
Discussion started by: navik_pathak
1 Replies
3. UNIX for Dummies Questions & Answers
Hi,
I have a char buf,ch; and the buf is filled with the result from MySQL server which I get like this numbytes = recv(sock, buf, 1024, 0));I have the followingcode to display the results
printf("received %ld bytes:\n",numbytes);
for(c=0;c<numbytes;c++){
ch = (char)buf;
... (2 Replies)
Discussion started by: alikims
2 Replies
4. Shell Programming and Scripting
Hi,
For the following complex code ,
<!-- ... (2 Replies)
Discussion started by: fed.linuxgossip
2 Replies
5. Programming
Hi All,
My main intension of is to convert the Hexstring stored in a char* into hex and then prefixing it with "0x" and suffix it with ','
This has to be done for all the hexstring char* is NULL.
Store the result prefixed with "0x" and suffixed with ',' in another char* and pass it to... (1 Reply)
Discussion started by: rvan
1 Replies
6. Shell Programming and Scripting
I am trying to match a character return from a website so that I can replace it. It is the '...' character (didnt even know it existed initially). The character apparently has the hex value of 2026, but in the script, attempting to substitute regular 3 periods is not working.
What am I... (2 Replies)
Discussion started by: Guyverix
2 Replies
7. Programming
Hello all. I need help...
How can I cenvert this 42ec93df826c804ea531c56594db453d54daad4b to normal text? What convertor I have to use?
Thanks. (12 Replies)
Discussion started by: escudo
12 Replies
8. Shell Programming and Scripting
i have this below string which i need to convert it to HEX. i have already tried it but it showing extra few things on it.. let me show what i have done and what is the output i am getting and what is the desired output
the input string is
"!\"\"\"\"\"\"\"!\"\"\"\"\"\"\""
which is... (4 Replies)
Discussion started by: vivek d r
4 Replies
9. Shell Programming and Scripting
I have a long string of hex (from ASN.1 data) where I need to find and change a particular hex value only and increment it. The hex pairs either side (84 and a7) of the value to increment will remain constant.
i.e. "84 <length> <value_to_increment> a7" starting with 00.
So end result:
... (11 Replies)
Discussion started by: securegooner
11 Replies
10. UNIX for Beginners Questions & Answers
Hi,
I'm looking to split the following hex string into rows of four elements.
I've tried the following but it doesn't seem to work. How can I tell sed to match based on a pair of number(s) and letter(s), and add a newline every 4 pairs?
In addition, I need to add another newline after every... (5 Replies)
Discussion started by: sand1234
5 Replies
LEARN ABOUT DEBIAN
filetest
filetest(3perl) Perl Programmers Reference Guide filetest(3perl)
NAME
filetest - Perl pragma to control the filetest permission operators
SYNOPSIS
$can_perhaps_read = -r "file"; # use the mode bits
{
use filetest 'access'; # intuit harder
$can_really_read = -r "file";
}
$can_perhaps_read = -r "file"; # use the mode bits again
DESCRIPTION
This pragma tells the compiler to change the behaviour of the filetest permission operators, "-r" "-w" "-x" "-R" "-W" "-X" (see perlfunc).
The default behaviour of file test operators is to use the simple mode bits as returned by the stat() family of system calls. However,
many operating systems have additional features to define more complex access rights, for example ACLs (Access Control Lists). For such
environments, "use filetest" may help the permission operators to return results more consistent with other tools.
The "use filetest" or "no filetest" statements affect file tests defined in their block, up to the end of the closest enclosing block (they
are lexically block-scoped).
Currently, only the "access" sub-pragma is implemented. It enables (or disables) the use of access() when available, that is, on most UNIX
systems and other POSIX environments. See details below.
Consider this carefully
The stat() mode bits are probably right for most of the files and directories found on your system, because few people want to use the
additional features offered by access(). But you may encounter surprises if your program runs on a system that uses ACLs, since the stat()
information won't reflect the actual permissions.
There may be a slight performance decrease in the filetest operations when the filetest pragma is in effect, because checking bits is very
cheap.
Also, note that using the file tests for security purposes is a lost cause from the start: there is a window open for race conditions (who
is to say that the permissions will not change between the test and the real operation?). Therefore if you are serious about security,
just try the real operation and test for its success - think in terms of atomic operations. Filetests are more useful for filesystem
administrative tasks, when you have no need for the content of the elements on disk.
The "access" sub-pragma
UNIX and POSIX systems provide an abstract access() operating system call, which should be used to query the read, write, and execute
rights. This function hides various distinct approaches in additional operating system specific security features, like Access Control
Lists (ACLs)
The extended filetest functionality is used by Perl only when the argument of the operators is a filename, not when it is a filehandle.
Limitation with regard to "_"
Because access() does not invoke stat() (at least not in a way visible to Perl), the stat result cache "_" is not set. This means that the
outcome of the following two tests is different. The first has the stat bits of "/etc/passwd" in "_", and in the second case this still
contains the bits of "/etc".
{ -d '/etc';
-w '/etc/passwd';
print -f _ ? 'Yes' : 'No'; # Yes
}
{ use filetest 'access';
-d '/etc';
-w '/etc/passwd';
print -f _ ? 'Yes' : 'No'; # No
}
Of course, unless your OS does not implement access(), in which case the pragma is simply ignored. Best not to use "_" at all in a file
where the filetest pragma is active!
As a side effect, as "_" doesn't work, stacked filetest operators ("-f -w $file") won't work either.
This limitation might be removed in a future version of perl.
perl v5.14.2 2010-12-30 filetest(3perl)