Monitoring command execution at regular intervals

I use these 2 methods to monitor command execution at regular intervals. One by using the command “watch” and another by using a small while statement.


Using watch command:
 # watch -n <time interval in seconds>  “command” or just  # watch  “command”


Examples:
# watch -n 10 "cat /proc/meminfo | grep -i Mem"      <- Watch Memory utilization at 10 seconds intervals
# watch -n 15 10 “du -sh |  grep /somefilesystem”     <- Watch disk utilization at 15 seconds interval.
# watch "ps aux|grep jboss"                                     <- Watch jboss process with default time interval


Using while statement:
while true; do <commands separated by semicolon>; sleep <time interval in seconds>; done  


Examples:

[adevaraju@hostxyz ~]$ while true; do cat /proc/meminfo | grep -i mem; uptime; echo; sleep 10; done
MemTotal:      4194480 kB
MemFree:         36776 kB
 01:52:51 up 14 days,  9:07,  1 user,  load average: 0.00, 0.00, 0.00


MemTotal:      4194480 kB
MemFree:         36652 kB
 01:53:01 up 14 days,  9:07,  1 user,  load average: 0.00, 0.00, 0.00


MemTotal:      4194480 kB
MemFree:         36776 kB
 01:53:11 up 14 days,  9:07,  1 user,  load average: 0.00, 0.00, 0.00


# while true; do echo Current time is  `date "+%H Hour: %M Minutes: %S Seconds"`; sleep 4; done
Current time is 01 Hour: 47 Minutes: 26 Seconds
Current time is 01 Hour: 47 Minutes: 30 Seconds
Current time is 01 Hour: 47 Minutes: 34 Seconds
Current time is 01 Hour: 47 Minutes: 38 Seconds
Current time is 01 Hour: 47 Minutes: 42 Seconds
Current time is 01 Hour: 47 Minutes: 46 Seconds
Current time is 01 Hour: 47 Minutes: 50 Seconds
Current time is 01 Hour: 47 Minutes: 54 Seconds
Current time is 01 Hour: 47 Minutes: 58 Seconds
Current time is 01 Hour: 48 Minutes: 02 Seconds
Current time is 01 Hour: 48 Minutes: 06 Seconds
#
PS:  “watch” command wouldn’t work properly if the command sets are complex. It will just display the result of first iteration and stay there forever.