Various Linux Commands - When you Need 'em!

From time to time I'll run into a request like "OMG, you HAVE to fix the mail queue RIGHT NOW!! We can't get our report and it's stopping us from submitting our POs in time for tomorrow's delivery!". Being the good (and prepared) Sysadmin that I am, I'm always ready to jump in and help out...My problem is that I don't always write down important commands where I should! (They're scattered all over the place, mostly in the form of post-it notes with poor handwriting and coffee stains)

Yes yes, I know it shouldn't take me 5 mins to search google to figure out how to re-run a sendmail queue, but these things slip your mind sometimes...especially when you have 6 people, including a manager and a director, looking over your shoulder waiting for the mail to 'start flowing'!

This is just a quick and dirty list of the commands that are specific to the things I deal with on a day-to-day basis. I won't go into much detail, so if you'd like more information: stop being so lazy and google it yourself!

Sendmail

'mailq' - List locally-queued mail
'mailq -Ac' - List sent, but undelivered, mail
'/usr/sbin/sendmail -v -q -d3.30' - Show current load in relation to sendmail.cf settings
'/usr/sbin/sendmail -qR /path/to/queue' - Force a mail queue run immediately
'tail /var/log/maillog' - Show output of mail log

Samba

'smbpasswd -a ' - Add user to samba
'smbpasswd -d/-e ' - Disable/enable samba user
'smbpasswd -n ' - Null password for user

Printing

'lpstat -t' - Show every printer, including queue
'/usr/bin/enable or disable' - Enable or disable printer, use the ABSOLUTE path
'lp -i -H restart' - Restart print job
'lpmove ' - Move a stalled job to different printer
'lprm -P ' - Remove print job
'lpadmin -P -E -v socket://ip.addr.of.prtr:9100' - Add and enable a new printer

Generic

'netstat -an' - Show all listening ports
'lsof -Pnl +M -i4' - Show files/daemons listening on specific ports/protocols
'w | wc' - List # of currently logged-on users
'finger ' - Not what you think...it's a legit command...I swear!
'chage -l ' - Show password aging for a user

I'll be updating this post with things that I think may be helpful to others...Personally, I didn't even know about the sendmail command for showing the settings vs. the current load...I found it on a sendmail development project blog from about 8 years ago...you never know!