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Shell Programming and Scripting
How to change only the x first characters of a string?
Post 302137859 by varungupta on Thursday 27th of September 2007 07:21:35 AM
09-27-2007
Quote:
Hi,
How can I replace x first characters from a string?
I have a file with... say 10000 entries as follows:
00123456781
00123456782
00123456783
...
What I want to do is change the leading "00" with for example "12"
The leading 00 can be in some files some other 1 or more digits e.g. "1" or "123" or what ever.
What would be the most efficient way of doing this as there might be even 20.000.000 entries in one file.
I wonder if the method could be embedded to a oneliner such as:
perl -i -p -e "s/old/new/g" filename
Thanks!
How can I replace x first characters from a string?
I have a file with... say 10000 entries as follows:
00123456781
00123456782
00123456783
...
What I want to do is change the leading "00" with for example "12"
The leading 00 can be in some files some other 1 or more digits e.g. "1" or "123" or what ever.
What would be the most efficient way of doing this as there might be even 20.000.000 entries in one file.
I wonder if the method could be embedded to a oneliner such as:
perl -i -p -e "s/old/new/g" filename
Thanks!
You can user sed.
sed 's/^[00]*/your replace string or number/' filename
I think you can use this when no. starts with 00* and in the starting of the line.
Otherwise you can use tr command to squeeze the multiple 0s.
visit: man tr
Thanks !!
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LEARN ABOUT DEBIAN
envext
ENVEXT(1) The Canonical Csound Reference ENVEXT(1) NAME
envext - Extracts the envelope of a file to a text file. . SYNTAX
envext [-flags] soundfile csound -U envext [-flags] soundfile INITIALIZATION
soundfile - Name of the input soundfile. The following flags are available for envext (The default values are stated in parenthesis): -o fnam Name of output filename (newenv) -w size (in seconds) of analysis window (0.25) The envext utility generates a text file containing time and amplitude pairs by finding the absolute peak within each window. EXAMPLE
Using the command (while in the manual directory): csound -U envext examples/mary.wav will produce the a text file containing the following: 0.000 0.000 0.000 0.000 0.250 0.000 0.500 0.000 0.750 0.000 1.249 0.170 1.499 0.269 1.530 0.307 1.872 0.263 2.056 0.304 2.294 0.241 2.570 0.216 2.761 0.178 3.077 0.011 3.251 0.001 3.500 0.000 Which shows the time for the peak amplitude within each measured window. CREDITS
Author: John ffitch 1995 AUTHORS
Barry Vercoe MIT Media Lab Author. Dan Ellis MIT Media Lab, Cambridge Massachussetts Author. COPYRIGHT
5.10 08/01/2011 ENVEXT(1)