Optimised way for search & replace a value on one line in a very huge file (File Size is 24 GB).


 
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Top Forums Shell Programming and Scripting Optimised way for search & replace a value on one line in a very huge file (File Size is 24 GB).
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Old 09-02-2011
As yazu has pointed out, if you are replacing the same number of bytes (or you can pad), you can use lower level programing, or do it with dd:
Code:
echo NEW |dd of=your-file bs=1 seek=offset-of-OLD count=3 conv=notrunc

You may need to adjust your options to dd if you are not using GNU dd. Be careful with this command, the original file is changed directly.
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STR_IREPLACE(3) 							 1							   STR_IREPLACE(3)

str_ireplace - Case-insensitive version ofstr_replace(3).

SYNOPSIS
mixed str_ireplace (mixed $search, mixed $replace, mixed $subject, [int &$count]) DESCRIPTION
This function returns a string or an array with all occurrences of $search in $subject (ignoring case) replaced with the given $replace value. If you don't need fancy replacing rules, you should generally use this function instead of preg_replace(3) with the i modifier. PARAMETERS
If $search and $replace are arrays, then str_ireplace(3) takes a value from each array and uses them to search and replace on $subject. If $replace has fewer values than $search, then an empty string is used for the rest of replacement values. If $search is an array and $replace is a string, then this replacement string is used for every value of $search. The converse would not make sense, though. If $search or $replace are arrays, their elements are processed first to last. o $search - The value being searched for, otherwise known as the needle. An array may be used to designate multiple needles. o $replace - The replacement value that replaces found $search values. An array may be used to designate multiple replacements. o $subject - The string or array being searched and replaced on, otherwise known as the haystack. If $subject is an array, then the search and replace is performed with every entry of $subject, and the return value is an array as well. o $count - If passed, this will be set to the number of replacements performed. RETURN VALUES
Returns a string or an array of replacements. EXAMPLES
Example #1 str_ireplace(3) example <?php $bodytag = str_ireplace("%body%", "black", "<body text=%BODY%>"); ?> NOTES
Note This function is binary-safe. Caution Replacement order gotcha Because str_ireplace(3) replaces left to right, it might replace a previously inserted value when doing multiple replacements. Example #2 in the str_replace(3) documentation demonstrates how this may affect you in practice. SEE ALSO
str_replace(3), preg_replace(3), strtr(3). PHP Documentation Group STR_IREPLACE(3)