there are numbers at the start of the line?

e.g. your regex is actually something more like "^[0-9]+ su" and depending on your unix variant (e.g. not a linux, possibly) you really mean egrep and not grep (although to a centos list, yes they're likely actually the same, but it still might be worth noting)

On Mon, Sep 16, 2013 at 12:27 PM, James B. Byrne byrnejb@harte-lyne.cawrote:

I am obviously missing something basic here but can someone explain to me what is wrong with the first statement, which returns nothing?

$ history | grep ^su $ history | grep su 2997 su -l 3024 su -l 3050 su -l 3054 su -l

Thanks,

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On Mon Sep 16 16:34:31 UTC 2013, zGreenfelder zgreenfelder at gmail.com wrote:

On Mon, Sep 16, 2013 at 12:27 PM, James B. Byrne <byrnejb at harte-lyne.ca>wrote:

...

I am obviously missing something basic here but can someone explain to me what is wrong with the first statement, which returns nothing?

$ history | grep ^su $ history | grep su 2997 su -l 3024 su -l 3050 su -l 3054 su -l

there are numbers at the start of the line?

Duh! Thanks. I could not see the forest for the trees I guess. I ended up with the following as I wanted a visual scan of all variants not just the most recent:

history | cut -f1-3 -d " " --complement | grep ^su

This is in the bash shell on CentOS-6.4.