Linux monitoring tools

Here is a list of various Linux monitoring tools and statistics files:

Overall Tools:
top, vmstat, sar, ps, pstree, ipcs

CPU:
top, mpstat, tload, /proc/cpuinfo, x86info

Memory:
free, /proc/meminfo, slabtop, /proc/slabinfo, ipcs

I/O:
iostat, vmstat, sar

sar examples:

To display CPU utilization:

sar 3 100

To display paging activity:

sar -B 3 100

To display swapping activity:

sar -W 3 100

To display block I/O activity:

sar -b 3 100

To display block I/O activity for each block device:

sar -d 3 100

To display network activity:

sar -n DEV 3 100