08-01-2011
Yes, the effect is the same, give or takes some renaming. Update in place destroys the original if anything goes wrong, and requires much more sophisticated tools. Most text tools truncate as they write. You need a very serious language, like PERL or C, to update the middle. Maybe it is a mindset hangover from tape, where, generally, the last thing you wrote is implicitly just before EOF.
A header could contain a file length and checksum as well as data type and format type magic strings, making updates more complex, but they are less popular in audio/video as you do not know these until the end, long after the header is written, and they do not want to go back and update, either.
Getting a patch to the software would be even nicer. I have patched stings in library file object code using a binary find and replace copier, and scary thing is, no checksum alarms went off! Maybe we need secure ELF? But these few bits are harder to locate and may break other things if you change them.
10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
I have a data file with over 500,000 records/lines that has the header throughout the file.
SEQ_ID Name Start_Date Ins_date Add1 Add2
1 Harris 04/02/08 03/02/08 333 Main Suite 101
2 Smith 02/03/08 01/23/08 287 Jenkins
SEQ_ID Name ... (3 Replies)
Discussion started by: psmall
3 Replies
2. Shell Programming and Scripting
Hi,
I'm trying to strip all lines between two headers in a file:
### BEGIN ###
Text to remove, contains all kinds of characters
...
Antispyware-Downloadserver.com (Germany)=http://www.antispyware-downloadserver.c
om/updates/
Antispyware-Downloadserver.com #2... (3 Replies)
Discussion started by: Trones
3 Replies
3. UNIX for Dummies Questions & Answers
Hello,
I have done much googling on this, but apparently not using the right keywords.
I am assuming there is some kind of header for each file on a disk which stores information such as mod time, access time, etc.
I have two questions:
1) is there a way to read this header directly,... (2 Replies)
Discussion started by: Allasso
2 Replies
4. Shell Programming and Scripting
Hi ,
I have a typical situation. I have 4 files and with different headers (number of headers is varible ).
I need to make such a merged file which will have headers combined from all files (comman coluns should appear once only).
For example -
File 1
H1|H2|H3|H4
11|12|13|14
21|22|23|23... (1 Reply)
Discussion started by: marut_ashu
1 Replies
5. Shell Programming and Scripting
Hi,
I have a folder that contains many (multiple) files
1.fasta
2.fasta
3.fasta
4.fasta
5.fasta
.
.
100's of files
Each such file have data in the following format
for example:
vi 1.fasta
>AB_1 200bp
MLKKPIIIGVTGGSGGGKTSVSRAILDSFPNARIAMIQHDSYYKDQSHMSFEERVKTNYDHPLAFDTDFM... (4 Replies)
Discussion started by: Lucky Ali
4 Replies
6. Shell Programming and Scripting
Hi ,
I have a .txt file in which I have multiple headers, the header record starts with $ symbol...like the first column name is $Account.
I have to keep the header in the first line and delete all the remaining headers which are in the file.
I tried using sort adc.txt | uniq -u , but my... (7 Replies)
Discussion started by: gaur.deepti
7 Replies
7. Shell Programming and Scripting
Hi,
I have a folder that contains many (multiple) files
1.fasta
2.fasta
3.fasta
4.fasta
5.fasta
.
.
100's of files
Each such file have data in the following format
for example:
vi 1.fasta
58 390
A
GTATACATTATTGATGAAGTCCACATGCTTTCTATGGGTGCCTTCAATGCGCTTTTAAAA (7 Replies)
Discussion started by: Lucky Ali
7 Replies
8. Shell Programming and Scripting
Hi I need to merge 4 files. The issue i am facing is all the files have headers and i do not want them in the final output file. Can anybody suggest how to do it? (5 Replies)
Discussion started by: Arun Mishra
5 Replies
9. UNIX for Dummies Questions & Answers
How do we append the file name to fasta file headers in multiple fasta-files in Linux? (10 Replies)
Discussion started by: Mauve
10 Replies
10. UNIX for Advanced & Expert Users
Hi. Unix rookie here. Been looking for a few days for reference documents on how BSD UNIX lays the logical file format onto a disk. Goal is to view/edit with hex editor for data repair. Lots of docs are available for how to use Unix commands (like xxd), but I want to learn the map of how Unix... (4 Replies)
Discussion started by: Chris_top_he_r
4 Replies
LEARN ABOUT FREEBSD
elf64_checksum
GELF_CHECKSUM(3) BSD Library Functions Manual GELF_CHECKSUM(3)
NAME
elf32_checksum, elf64_checksum, gelf_checksum -- return the checksum of an ELF object
LIBRARY
ELF Access Library (libelf, -lelf)
SYNOPSIS
#include <libelf.h>
long
elf32_checksum(Elf *elf);
long
elf64_checksum(Elf *elf);
#include <gelf.h>
long
gelf_checksum(Elf *elf);
DESCRIPTION
These functions return a simple checksum of the ELF object described by their argument elf. The checksum is computed in way that allows its
value to remain unchanged in presence of modifications to the ELF object by utilities like strip(1).
Function elf32_checksum() returns a checksum for an ELF descriptor elf of class ELFCLASS32.
Function elf64_checksum() returns a checksum for an ELF descriptor elf of class ELFCLASS64.
Function gelf_checksum() provides a class-independent way retrieving the checksum for ELF object elf.
RETURN VALUES
These functions return the checksum of the ELF object, or zero in case an error was encountered.
ERRORS
These functions may fail with the following errors:
[ELF_E_ARGUMENT] Argument elf was NULL.
[ELF_E_ARGUMENT] Argument elf was not a descriptor for an ELF file.
[ELF_E_ARGUMENT] The ELF descriptor elf was not opened for reading or updating.
[ELF_E_CLASS] For functions elf32_checksum() and elf64_checksum(), ELF descriptor elf did not match the class of the called function.
[ELF_E_HEADER] The ELF object specified by argument elf had a malformed executable header.
[ELF_E_RESOURCE] An out of memory condition was detected during processing.
[ELF_E_SECTION] The ELF object specified by argument elf contained a section with a malformed section header.
[ELF_E_VERSION] The ELF object was of an unsupported version.
SEE ALSO
strip(1), elf(3), gelf(3)
BSD
August 29, 2006 BSD