Commands by leprasmurf (5)

  • I have come across multiple situations where I could only get to a server from a very restrictive bounce point which would not allow file transfers. I was able to uuencode a file, copy the output to a text file over putty, and then uudecode the file to transfer it. This works with any kind of file. Show Sample Output


    -4
    uuencode -m <filename> <filename>
    leprasmurf · 2009-12-22 15:28:59 3
  • Needed to get the Mac of various devices on a solaris box, but didn't have root. This command used awk to display the Network device, the IP, and the MAC a line at a time.


    1
    ifconfig -a | nawk 'BEGIN {FS=" "}{RS="\n"}{ if($1~ /:/) {printf "%s ", $1}}{ if($1=="inet") {print " -- ",system("arp "$2)}}'|egrep -v "^[0-9]$"
    leprasmurf · 2009-03-02 23:15:13 5
  • Telnet will make a tcp connection to a remote ip/port to test connectivity. If it times out, it's not reaching the host (maybe the firewall is blocking it). If connection is refused, it's reaching the host, but either the service is not listening on that port, or it's locked. Show Sample Output


    -2
    telnet <ip> <port>
    leprasmurf · 2009-02-12 19:11:03 12
  • Bash shortcut to work with the last argument of your last command Show Sample Output


    15
    file !$
    leprasmurf · 2009-02-06 15:41:08 17
  • Quick command to check if Perl library is installed on your server. Show Sample Output


    0
    perl -e "use SOAP::Lite"
    leprasmurf · 2009-02-06 15:26:37 16

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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"

Get line number 12 (or n) from a file
Extracts only file number 12 from file. It's meant for text files. Replace 12 with the number you want. First line starts at 1 not 0. We use q on next line so doesn't process any line more.

return external ip
Get your ip address, hostname, ASN and geolocation information. If you want just one field as a text response you can also get that,eg curl ipinfo.io/ip

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

list block devices
Shows all block devices in a tree with descruptions of what they are.

Use /dev/full to test language I/O-failsafety
The Linux /dev/full file simulates a "disk full" condition, and can be used to verify how a program handles this situation. In particular, several programming language implementations do not print error diagnostics (nor exit with error status) when I/O errors like this occur, unless the programmer has taken additional steps. That is, simple code in these languages does not fail safely. In addition to Perl, C, C++, Tcl, and Lua (for some functions) also appear not to fail safely.

ShellCheck all the bash/sh script under a specific directory excluding version control
This is a commodity one-liner that uses ShellCheck to assure some quality on bash and sh scripts under a specific directory. It ignores the files in .git directory. Just substitute "./.git/*" with "./.svn/*" for older and booring centralized version control. Just substitute ShellCheck with "rm" if your scripts are crap and you want to get rid of them :)

Find the package that installed a command

find the longest command in your history

Downmix from stereo to mono and play radio stream with mplayer
The solution to a year long (and extremely frustrating) problem I've had, caused by the fact that I only have one speaker; this command downmixes the stream to monophonic output, making sure I don't miss any of the music. NOTE: When stream is in .m3u format, a -playlist option is required, as shown below: $ mplayer -af pan=1:0.5:0.5 -channels 1 -playlist radiostream.m3u This command works great with aliases for various channels in .bashrc. Sample below: $ alias radio1='mplayer -af pan=1:0.5:0.5 -channels 1 radio1stream.pls'


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