> My generic question is: When I'm using a pipe line series of commands > do I use up more/less space than doing things in sequence?
When you use a pipe you don't need the space to store intermediate results between the two programs. Thepipe is backed by a small system-allocated RAM buffer (4k under linux AFAIK) and program execution is controlled according to the amount of data in the buffer. Not having to save intermediate results generally means that you will need less disk space: this is especially true in the mysqldump-gzip example as the uncompressed dump will not be written to the disk at any stage. Note however (this is the "it depends" part :) that piping does not affect whatever the programs might allocate or save internally: in your second example (which does not involve any disk writing in either case) "sort" needs to see the complete input before producing any output, so it will allocate enough memory to store it whether it is invoked alone or as part of a pipeline (in which case it will also stall the downstream pipeline section until the upstream pipe is closed). HTH, andrea
