Commands by terrywang (1)

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Using awk to sum/count a column of numbers.
Takes a input file (count.txt) that looks like: 1 2 3 4 5 It will add/sum the first column of numbers.

Less a grep result, going directly to the first match in the first file
Really useful way to combine less and grep while browsing log files. I can't figure out how to make it into a true oneliner so paste it into a script file called lgrep: Usage: lgrep searchfor file1 [file2 file3] Advanced example (grep for an Exception in logfiles that starts with qc): lgrep Exception $(find . -name "qc*.log")

Sum size of files returned from FIND

Suppress output of loud commands you don't want to hear from
Suppresses all output to /dev/null. This could be expanded to check for a -l command line option to log the stderr to a file maybe -l file or -l to log to default quietly.log. I'm finding that I use it more often than one would think.

Remove all zero size files from current directory (not recursive)
works only in zsh

View network activity of any application or user in realtime
The "-r 2" option puts lsof in repeat mode, with updates every 2 seconds. (Ctrl -c quits) The "-p" option is used to specify the application PID you want to monitor. The "-u' option can be used to keep an eye on a users network activity. "lsof -r 2 -u username -i -a"

Check if a machine is online with better UI
I have used single packet, and in a silent mode with no display of ping stats. This is with color and UI improvement to the http://www.commandlinefu.com/commands/view/10220/check-if-a-machine-is-online. It is as per the enhancements suggested.

Execute a command with a timeout
In this example the command "somecommand" will be executed and sent a SIGALARM signal if it runs for more than 10 seconds. It uses the perl alarm function. It's not 100% accurate on timing, but close enough. I found this really useful when executing scripts and commands that I knew might hang E.g. ones that connect to services that might not be running. Importantly this can be used within a sequential script. The command will not release control until either the command completes or the timeout is hit.

nmap IP block and autogenerate comprehensive Nagios service checks
More info here: http://nagioswiki.com/wiki/index.php/Autocreating_Nagios_Configuration_with_Nmap_and_Nmap2Nagios.pl

Easily decode unix-time (funtion)
More recent versions of the date command finally have the ability to decode the unix epoch time into a human readable date. This function makes it simple to utilize this feature quickly.


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