sed -n '10000000,10000020p' filename
You might be able to speed that up a little like this:
sed -n '10000000,10000020p; 10000021q' filename
In those commands, the option -n
causes sed
to "suppress automatic printing of pattern space". The p
command "print[s] the current pattern space" and the q
command "Immediately quit[s] the sed script without processing any more input..." The quotes are from the sed
man
page.
By the way, your command
tail -n 10000000 filename | head 10
starts at the ten millionth line from the end of the file, while your "middle" command would seem to start at the ten millionth from the beginning which would be equivalent to:
head -n 10000010 filename | tail 10
The problem is that for unsorted files with variable length lines any process is going to have to go through the file counting newlines. There's no way to shortcut that.
If, however, the file is sorted (a log file with timestamps, for example) or has fixed length lines, then you can seek into the file based on a byte position. In the log file example, you could do a binary search for a range of times as my Python script here* does. In the case of the fixed record length file, it's really easy. You just seek linelength * linecount
characters into the file.
* I keep meaning to post yet another update to that script. Maybe I'll get around to it one of these days.
If you don't have rename
(it's a really short Perl script) or your rename is the more simplistic util-linux version or you simply want to know how to make your command work: you just need to send it to the shell for execution:
find spec -name "*_test.rb" -exec sh -c 'echo mv "$1" "$(echo "$1" | sed s/test.rb\$/spec.rb/)"' _ {} \;
Best Answer
Are you sure that that is actually the filename? On recent Linux distributions
ls
displays filenames with spaces in quotes by default. Tryls -N
to be sure.From the man page: