08-24-2009
Best place to look for a detailed explanation is RFC 1071
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Does anyone know the answer to this?
When I run "sum -r" on a file that I've down loaded from the sco website, the 1st set of numbers differs from the checksum on the download page but the
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If I try to install the patch, I get errors.
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say i have these many file in a directory named exam.
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on the... (2 Replies)
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3. Shell Programming and Scripting
Input
#HAC0253
EFVHIJHIJEFVTHIJOPKOPKTEFVEFVEFVOPKHIJOPKOPKHIJTTEFVEFVTEFV
#BASFS12
EFVEFVHIJEFVEFVTOPKEFVOPKTHIJTTHIJOPK
#ACG5115
TEFVEFVOIJEFVHIJHIJOPKOPKHIJHIJTTEFVEFVOPKTTEFVEFVOPKHIJOPKOPKOPK
#ECG5114
IJTOPKHIJEFVOEFVEFVOPKTTEFVEFVOPKHIJOPKOPKOPK
.
.
Output (5 Replies)
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4. Shell Programming and Scripting
Hello,
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Friends,
I need help with the following in UNIX.
Merge all csv files in one folder considering only 1 header row and ignoring header of all other files.
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Hello
I am communicating with two devices using my computer over UDP protocol. The application is running fine. When I monitored the UDP traffic using Wireshark software, I found that there were too many Checksum errors.
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7. Shell Programming and Scripting
Hi,
I have an input like this
1 2 3 4
2 3 4 5
4 5 6 7
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8. Shell Programming and Scripting
Hello There...
I have a sample input file ..
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I've been struggling with this one for quite a while and cannot seem to find a solution for this find/replace scenario. Perhaps I'm getting rusty.
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LEARN ABOUT NETBSD
in4_cksum
IN_CKSUM(9) BSD Kernel Developer's Manual IN_CKSUM(9)
NAME
in_cksum, in4_cksum, in6_cksum -- compute Internet checksum
SYNOPSIS
uint16_t
in_cksum(struct mbuf *m, int len);
uint16_t
in4_cksum(struct mbuf *m, uint8_t nxt, int off, int len);
uint16_t
in6_cksum(struct mbuf *m, uint8_t nxt, int off, int len);
DESCRIPTION
These functions are used to compute the ones-complement checksum required by IP and IPv6. The in4_cksum() function is used to compute the
transport-layer checksum required by tcp(4) and udp(4) over a range of bytes starting at off and continuing on for len bytes within the mbuf
m.
If the nxt parameter is non-zero, it is assumed to be an IP protocol number. It is also assumed that the data within m starts with an IP
header, and the transport-layer header starts at off; a pseudo-header is constructed as specified in RFC768 and RFC793, and the pseudo-header
is prepended to the data covered by the checksum.
The in6_cksum() function is similar; if nxt is non-zero, it is assumed that m starts with an IPv6 header, and that the transport-layer header
starts after off bytes.
The in_cksum() function is equivalent to in4_cksum(m, 0, 0, len).
These functions are always performance critical and should be reimplemented in assembler or optimized C for each platform; when available,
use of repeated full-width add-with-carry followed by reduction of the sum to a 16 bit width usually leads to best results. See RFC's 1071,
1141, 1624, and 1936 for more information about efficient computation of the internet checksum.
RETURN VALUES
All three functions return the computed checksum value.
SEE ALSO
inet(4), inet6(4), tcp(4), udp(4), protocols(5), mbuf(9)
STANDARDS
These functions implement the Internet transport-layer checksum as specified in RFC768, RFC793, and RFC2460.
BUGS
The in6_cksum() function currently requires special handling of link-local addresses in the pseudo-header due to the use of embedded scope-
id's within link-local addresses.
BSD
May 22, 2001 BSD