Measuring RAM usage of a program

time is a built-in of your shell. If you like time but need more information, try GNU time in verbose (-v) mode:

/usr/bin/time -v sleep 5               
    Command being timed: "sleep 5"
    User time (seconds): 0.00
    System time (seconds): 0.00
    Percent of CPU this job got: 0%
    Elapsed (wall clock) time (h:mm:ss or m:ss): 0:05.00
    Average shared text size (kbytes): 0
    Average unshared data size (kbytes): 0
    Average stack size (kbytes): 0
    Average total size (kbytes): 0
    Maximum resident set size (kbytes): 2144
    Average resident set size (kbytes): 0
    Major (requiring I/O) page faults: 0
    Minor (reclaiming a frame) page faults: 179
    Voluntary context switches: 2
    Involuntary context switches: 1
    Swaps: 0
    File system inputs: 0
    File system outputs: 0
    Socket messages sent: 0
    Socket messages received: 0
    Signals delivered: 0
    Page size (bytes): 4096
    Exit status: 0

Search the package "time" or "gnutime" in your package manager.

You can use tstime to measure the highwater memory usage (RSS and virtual) of a process.

For example:

$ tstime date       
Tue Aug 16 21:35:02 CEST 2011

Exit status: 0

pid: 31169 (date) started: Tue Aug 16 21:35:02 2011
        real   0.017 s, user   0.000 s, sys   0.000s
        rss      888 kb, vm     9764 kb

It also supports a more easy to parse output mode (-t).

Maybe overkill, but I just found that valgrind has a nice tool named massif. I tested it on xterm:

valgrind --trace-children=yes --tool=massif xterm
ms_print massif.out.* | less

And you obtain a nice memory usage graph:

    MB
4.230^                     #                    :::::::  :::      @@:     ::: 
     |   @                 #:::@::@@:::::@::::::: :: : ::: :::::::@ ::::::: ::
     |   @               ::#:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
     |   @::::@@:::::::::: #:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
     |   @::: @ :: ::: : : #:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
     |   @::: @ :: ::: : : #:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
     |   @::: @ :: ::: : : #:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
     |   @::: @ :: ::: : : #:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
     |   @::: @ :: ::: : : #:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
     |   @::: @ :: ::: : : #:: @: @ ::: :@: :: :: :: : ::: ::: : :@ :: : :: ::
   0 +----------------------------------------------------------------------->Mi
     0                                                                   292.4

along with overly detailed memory usage info. Details in the valgrind manual.

Programs will run about 20x slower though. Also, I ran some commands inside the xterm. Their memory footprint has been taken into account because the --trace-children=yes the option is there!