10 super-cool Linux hacks you did not know about -1

1. Run top in batch mode

 time delay and the number of iterations can be configured, giving you the ability to dictate the data collection as you see fit. Here's an example:

top -b -d 10 -n 3 >> top-file

We have top running in batch mode (-b). It's going to refresh every 10 seconds, as specified by the delay (-d) flag, for a total count of 3 iterations (-n).

2. Write to more than one file at once with tee

 In general, with static data, this is not a problem. You simply repeat the write operation. With dynamic data, again, this is not that much of a problem. You capture the output into a temporary variable and then write it to a number of files. But there's an easier and faster way of doing it, without redirection and repetitive write operations. The answer: tee.
tee is a very useful utility that duplicates pipe content. Now, what makes tee really useful is that it can append data to existing files, making it ideal for writing periodic log information to multiple files at once.
Here's a great example:

ps | tee file1 file2 file3 

 

3. Unleash the accounting power with pacct

Did you know that you can log the completion of every single process running on your machine? You may even want to do this, for security, statistical purposes, load optimization, or any other administrative reason you may think of. By default, process accounting (pacct) may not be activated on your machine. You might have to start it:

/usr/sbin/accton /var/account/pacct

Once this is done, every single process will be logged. You can find the logs under /var/account. The log itself is in binary form, so you will have to use a dumping utility to convert it to human-readable form. To this end, you use the dump-acct utility.

dump-acct pacct 

 

4. Dump utmp and wtmp logs

Like pacct, you can also dump the contents of the utmp and wtmp files. Both these files provide login records for the host. This information may be critical, especially if applications rely on the proper output of these files to function.
dump-utmp /var/log/wtmp