if contents does not matter, then seek is better then write operation (considering faster operation with lesser Hardidsk noise polution :p )… anyways GB big files are usually diskimage (my assumption, in my case it was swapfile), which later are formated using mk-blabla file-system structure… thus

dd if=/dev/zero of=somefile bs=1 seek=1G count=0

Greetingz

python -c 'import sys; a1="abcdefghijklmnopqrstuvwxyz" ; a2=a1[::-1] ; a=a1+a2[1:] ; size=100000 ; [sys.stdout.write(a) for i in range(1,size,len(a))]' # > myfile.dat

Cheers!

python -c 'import sys; a1="abcdefghijklmnopqrstuvwxyz" ; a2=a1[::-1] ; a=a1+a2[1:] ; size=100000 ; for i in range(1,size,len(a)): sys.stdout.write(a)' # > myfile.dat

Cheers!

while true
do
# commands
done

to use this:

while :
do
# commands
done

Works for the same reason as stated in my previous comment above; the : (colon) command is a do-nothing (shell built-in) command that returns true as its exit code, but is faster to run than the “true” command that does the same, but “true” is an actual binary (executable file) on disk, and hence (except for caching) has to be loaded into memory each time through the while loop, leading to a small overhead.

- Vasudev

Smiley of death is a nice term, hadn’t come across it before.

In that, the colon is a do-nothing command (that returns true, BTW) and the rest of the line is the redirection. But even that can be made shorter – although by just 1 character :) , just use:

> file.txt

Odd though it may seem, that’s a legal shell command.

Thinking mathematically, one could say that “a zero-length or null command is also a command” :), so the shell allows it …

- Vasudev