in-memory file

[prajjwal]

I am looking for something which may be called an in-memory file. The very idea is, I do not want to create any temporary file while processing using a shell script. Is this by any chance feasible?

In most of the cases, using pipe solves the purpose but in some cases not.
E.g.
# some massive computation > smalltempfile1
# wc -l smalltempfile1
# head -5 smalltempfile1

Alternate way..
# some massive computation | wc -l
# some massive computation | head -5

But this will hit performance.. The above is just an example, hence please do not consider this as a benchmark when you answer. There are plenty of places where I felt the requirement of an in-memory file.

Need your help...

[meton_magis]

run a
man mount
and look for tmpfs.

tmpfs creates a temprary filesystem in memory. anything saved there will be saved in ram only, and never go to the hard drive. You do have to explicitely delete files here to free up ram usage however, and if you exceede your physical ram on your server, it will be saved to swap space on your hard drive, creating more overhead than there would be if you had just saved there to begin with.

another option may be
Named pipe - Wikipedia, the free encyclopedia
but I have no idea how those work, so you'd have to research them yourself.

[Rubberman]

As what meton_magis said, with one addendum. You can limit the size of the file system with the mount option size=bytes. For example, to create a 100M ram-based file system, you could do this:

mkdir /mnt/tmp
mount -t tmpfs /dev/shr /mnt/tmp -o size=100m