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Handy one-liners

November 22 2008 : posted under linux programming perl

While creating websites I often find the need to manipulate files in all sorts of ad-hoc ways.

Things that are hard to do by hand, but you don’t want to write a whole program for - you’ll just use it once and throw it away.

Linux/Unix excels at this sort of task - there is a rich selection of tools and plenty of ready made recipes.

From:

http://www.ibm.com/developerworks/linux/library/l-p101/

I often use

> cat test
aaa
bbb
ccc
ddd
aaa
> perl -pi -e's/aaa/bbb/' test
> cat test
bbb
bbb
ccc
ddd
bbb

http://student.northpark.edu/pemente/sed/sed1line.txt gives me a way to print out just the lines near an error is being generated (handy when there is one error line in a gigabyte of data)

sed -n '7560,7570p' my_big_file.txt

Though day to day grep, find, locate and thier friends usually do all I need.

I tried working on Windows a while ago - but found I just couldn’t work effectively without these tools.