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Top Forums UNIX for Advanced & Expert Users use of sed over cat to merge files Post 302147781 by gus2000 on Wednesday 28th of November 2007 12:36:43 PM
Old 11-28-2007
I agree that there's little you can do about making a 80GB edit more efficient.

The reason your "sed" command did not work is because you used single-quotes around the expression, which prevents the variables from being evaluated:

Code:
# i=100
# echo "$i"
100
# echo '$i'
$i

So if you need to reference a variable, you can't use the single-quotes. But if you use double-quotes, you'll need to escape anything that the shell will evaluate but that you need to be literal.
 

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ESCAPESHELLARG(3)							 1							 ESCAPESHELLARG(3)

escapeshellarg - Escape a string to be used as a shell argument

SYNOPSIS
string escapeshellarg (string $arg) DESCRIPTION
escapeshellarg(3) adds single quotes around a string and quotes/escapes any existing single quotes allowing you to pass a string directly to a shell function and having it be treated as a single safe argument. This function should be used to escape individual arguments to shell functions coming from user input. The shell functions include exec(3), system(3) and the backtick operator. On Windows, escapeshellarg(3) instead removes percent signs, replaces double quotes with spaces and adds double quotes around the string. PARAMETERS
o $arg - The argument that will be escaped. RETURN VALUES
The escaped string. EXAMPLES
Example #1 escapeshellarg(3) example <?php system('ls '.escapeshellarg($dir)); ?> SEE ALSO
escapeshellcmd(3), exec(3), popen(3), system(3), backtick operator. PHP Documentation Group ESCAPESHELLARG(3)
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