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I'm a newbie in Linux scripting, especially for using sed and awk commands. For now I'm trying to filter a really big log file and wondering if there are any alternatives for my commands? or some optimizing? here is the code:

nice -20 sed '/./{H;$!d;};x;/37455299339/!d' 1.txt > /tmp/new.txt
nice -20 sed -n '/Acct-Status-Type/,/NAS-Identifier/p' /tmp/new.txt > /tmp/new_1.txt
rm /tmp/new.txt
nice -20 sed '/Acct-Status-Type/{x;p;x;}' /tmp/new_1.txt > /tmp/new_2.txt
rm /tmp/new_1.txt
nice -20 less /tmp/new_2.txt | grep -A1 -B1 37455299339 | grep -A1 -B1 User-Name > new_3.txt
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You can try sed -i – Bernhard Apr 12 '13 at 6:53
sed -i for which command? for all? – user37033 Apr 12 '13 at 7:28
Yep, it updates the files in place, so you can get rid of the > and rm parts. – Bernhard Apr 12 '13 at 7:58
Rather than providing the sed commands, you should explain the problem you're actually trying to solve. – frostschutz Apr 12 '13 at 11:02
@user37033 Whith {H;$!d;}, you're storing whole input file in ram. In actual state of knowledge, we could'not help you. Give us some lines of input as sample and explain what's your goal. – F. Hauri Jun 16 '13 at 7:58

As first step, I would remove all temporary files and use pipe instead: from first sed you may pipe stdout to second one and then to third one. Then, your less command is useless: just pipe again from the third sed to grep.

Using pipe you will have many benefits: first you will not waste your disk space, second, you will not wait for all these disk I/O.

For better finding a solution, you should tell us what is currently blocking you: is it one of the sed commands? Which one?

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