cc: [email protected]
Subject: Re: [ast-developers] [RFE] read until content matches pattern?
--------
> The read command has "-d delim" to read until delimiter delim. I like
> to have a new option "-P pattern" read until the content matches the
> pattern "pattern" or until EOF. Currently I can do this only by
> reading the input stream one character at the time, then concatenate
> each character and match that against "pattern". This is an incredibly
> slow way compared to awk's line matching actions.
>
> David
>
If you are reading from a file, then you can use
exec n<$ pattern
to seek to the next line that matches pattern where n is the file
number.
This can be following by a read to get the line containing
the pattern.
This does not work for non-seekable files.
For example to find and print all lines in a file that contain at least five
consecutive digits , you can do
while exec {n}<# *{5}(\d)* && read -r
do print -r -- "$REPLY"
done {n}< file
David Korn
[email protected]
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