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BOOK: Beginning Linux Programming, 4th Edition ISBN 978-0-470-14762-7
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Old March 8th, 2015, 11:03 AM
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Default shell mini cd manager question

chapter 2 mini CD manager. Can any one please explain the next code:
in the function remove_records():

grep -v "^${cdcatnum}," $title_file > $temp_file
mv $temp_file $title_file
grep -v "^${cdcatnum}," $tracks_file > $temp_file
mv $temp_file $tracks_file

any help will be greatly appreciated.
thank you.
Old June 16th, 2018, 03:11 PM
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Default what does the grep do

the code finds lines in the file named title_file
Actually the code finds the lines that do NOT begin with the specified pattern
and saves all these lines in a temporary file. Then the next line renames the temporary file
and gives it the name of the existing file, so it actually substitutes the existing file with a file that does not have the specific lines , so in other words the specific lines were removed.

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