Commands by px (3)

  • This one-liner will use strace to attach to all of the currently running apache processes output and piped from the initial "ps auxw" command into some awk. Show Sample Output

    ps auxw | grep sbin/apache | awk '{print"-p " $2}' | xargs strace
    px · 2011-03-14 21:45:22 7
  • This one-liner is for cron jobs that need to provide some basic information about a filesystem and the time it takes to complete the operation. You can swap out the di command for df or du if that's your thing. The |& redirections the stderr and stdout to the mail command. How to configure the variables. TOFSCK=/path/to/mount FSCKDEV=/dev/path/device or FSCKDEV=`grep $TOFSCK /proc/mounts | cut -f1 -d" "` MAILSUB="weekly file system check $TOFSCK " Show Sample Output

    ( di $TOFSCK -h ; /bin/umount $TOFSCK ; time /sbin/e2fsck -y -f -v $FSCKDEV ; /bin/mount $TOFSCK ) |& /bin/mail $MAILTO -s "$MAILSUB"
    px · 2010-10-24 00:35:23 1
  • Use GNU/screen as a terminal emulator for anything serial console related. screen /dev/tty eg. screen /dev/ttyS0 9600 MacOSX: Cheat Sheet: Show Sample Output

    screen /dev/tty<device> 9600
    px · 2010-07-20 09:12:13 3

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Get all files of particular type (say, PDF) listed on some wegpage (say,
This example command fetches '' webpage and then fetches+saves all PDF files listed (linked to) on that webpage. [*Note: of course there are no PDFs on This is just an example]

ISO info
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Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

display emerge.log date in a human friendly way
gentoo only or gentoo-like linux distributions.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Shows the torrent file name along with the trackers url
Replace * with any filename matching glob or an individual filename

nohup that doesn't generate nohup.out
I'm sure this can be piped into another way. Please share!

Redirect incoming traffic to SSH, from a port of your choosing
Stuck behind a restrictive firewall at work, but really jonesing to putty home to your linux box for some colossal cave? Goodness knows I was...but the firewall at work blocked all outbound connections except for ports 80 and 443. (Those were wide open for outbound connections.) So now I putty over port 443 and have my linux box redirect it to port 22 (the SSH port) before it routes it internally. So, my specific command would be: $iptables -t nat -A PREROUTING -p tcp --dport 443 -j REDIRECT --to-ports 22 Note that I use -A to append this command to the end of the chain. You could replace that with -I to insert it at the beginning (or at a specific rulenum). My linux box is running slackware, with a kernel from circa 2001. Hopefully the mechanics of iptables haven't changed since then. The command is untested under any other distros or less outdated kernels. Of course, the command should be easy enough to adapt to whatever service on your linux box you're trying to reach by changing the numbers (and possibly changing tcp to udp, or whatever). Between putty and psftp, however, I'm good to go for hours of time-killing.

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