#!/bin/bash
################################################################################
# A simple program to log memory usage of a command.
#
# Usage: memlog <cmd> [<params>]
#
# The logfile written is ./<cmd>.log and has the form:
#     YYYYMMDD HH:MM:SS|<resident> <virtual>
################################################################################

PROGNAME=$(basename $0)

######
# Write to the log file
######

log()
{
    DT=$(date +"%Y%m%d %H:%M:%S:")
    echo "$DT|$1 $2" >>$LOG
}

######
# Give user some help
######

usage()
{
    echo "Usage: $PROGNAME <cmd> [<params>]"
    echo "This will attempt to start the  '<cmd> [<params>]' program, and will"
    echo "write a log file at ./<cmd>.log."
    exit 10
}

######
# Get parameters.
######

if [ $# -lt 1 ]; then
    usage
fi

CMD=$*
LOG="$1.log"

######
# Start command
######

$CMD &
PID=$!

######
# Loop, getting $PID memory usage.
######

while true; do
    sleep 1
    DATA=$(ps -o rss,vsize -p $PID | tail -1)
    RSS=$(echo $DATA | awk '{print $1}')
    VSIZE=$(echo $DATA | awk '{print $2}')

    # if child process finished, break out
    if [ "$RSS" == "RSS" ]; then
	break
    fi

    log $RSS $VSIZE
done