Pretty print json in python

For python2

I wanted to show what variables are in use in a function, and I wanted to see it in a nicer format than a really long, single line.

import inspect, json
def function():
print json.dumps(locals(),indent=3,separators=(',',': '))

Bonus

To view what parameters were passed in to a function, add these.

def caller_args():
   frame = inspect.currentframe()
   outer_frames = inspect.getouterframes(frame)
   caller_frame = outer_frames[1][0]
   return inspect.getargvalues(caller_frame)

def function():
print caller_args()

References

  1. https://stackoverflow.com/questions/29935276/inspect-getargvalues-throws-exception-attributeerror-tuple-object-has-no-a#29935277
  2. compact encoding https://docs.python.org/2/library/json.html

					

Get Windows license key from your hardware in Linux

If you are running on hardware that originally came with a licensed Microsoft Windows operating system, you should check to see if you can get the license key from your hardware.

sudo hexdump -s 56 -e '"MSDM key: " /29 "%s\n"' /sys/firmware/acpi/tables/MSDM
MSDM key: 12345-09876-ABCDE-FGHIJ-ZYXWV (obscured, of course)

Or another way:

sudo cat /sys/firmware/acpi/tables/MSDM | strings

I never came across this tidbit until today! Apparently it is well-known throughout the Internet.

References

Weblinks

  1. Found it first at https://solus-project.com/forums/viewtopic.php?f=11&t=8663
  2. Strings method https://superuser.com/questions/637971/how-do-i-get-out-my-embedded-windows-8-key-from-a-linux-environment#638033

Find running X sessions

tl;dr

{ ps -eo pid,command | awk '/-session/ {print $1}' | while read thispid; do cat /proc/${thispid}/environ | tr '\0' '\n' | grep "DISPLAY" | sed -e "s/^/${thispid} $( stat -c '%U' /proc/${thispid}/comm ) $( basename $( readlink -f /proc/${thispid}/exe ) ) /;"; done; } 2>/dev/null | grep -iE "xfce|cinnamon"

Explanation

I was working on a shell script that affects the running desktop environments. In order to find the running processes, owners, executable, and display session, I whipped up this one-liner.

Obviously here, I limit my searches to specific types of desktop environments. I was getting a dbus-daemon and at-spi2-registryd which I neither understand nor care about, so I added the regular expression search at the end. Feel free to modify for your own use.

Example output:

$ { ps -eo pid,command | awk '/-session/ {print $1}' | while read thispid; do cat /proc/${thispid}/environ | tr '\0' '\n' | grep "DISPLAY" | sed -e "s/^/${thispid} $( stat -c '%U' /proc/${thispid}/comm ) $( basename $( readlink -f /proc/${thispid}/exe ) ) /;"; done; } 2>/dev/null | grep -iE "xfce|cinnamon"
1791 bgstack15-local xfce4-session DISPLAY=:0

Shell one-liners for manipulating symlinks

Showing symlink targets

I was trying to clean up a directory filled with files and symlinks. Many of the symlinks’ targets did not exist anymore (old package versions). I wrote a few one-liners to help me examine and clean up the directory.

Here’s the first one-liner.

find . -type l -print0 | sed -e 's/\.\///g;' | xargs -0 -n1 | while read line; do canon=$( readlink -f "${line}" 2>/dev/null ); test -e "${canon}" && echo "${line} is $( /bin/ls -d --color=always "${canon}" )" || echo "INVALID ${line}"; done

In expanded form:
find . -type l -print0 | \
sed -e 's/\.\///g;' | \
xargs -0 -n1 | \
while read line; do \
canon=$( readlink -f "${line}" 2>/dev/null );
test -e "${canon}" && echo "${line} is $( /bin/ls -d --color=always "${canon}" )" || echo "INVALID ${line}";
done

The find command lists symlinks in the current directory, with special null characters as the separators. This will allow correct operation with spaces in filenames. You don’t normally encounter this in GNU/Linux, but you never know!

The sed removes the dot slash ./ from the beginning of filenames. I just don’t like seeing that. If I had selected find * earlier, I wouldn’t need the sed command, but I would miss any files whose names begin with dot (e.g., .gitignore) and I would still find file . which I would have to exclude somehow anyway (well, not here because I’m searching for symlinks, but I personally never try to run find * no matter what).

xargs -0 -n1 now removes the null character separators, and feeds each individual entry one at a time to the next command.

While: So for each entry, read the symlink. If the target is a file, display it in whatever color ls would show it (without entering directories), because colors are pretty! Otherwise, print the line with “INVALID” in front of it.

Cleaning up the invalid symlinks

find . -type l -print0 | sed -e 's/\.\///g;' | xargs -0 -n1 | while read line; do canon=$( readlink -f "${line}" 2>/dev/null ); test -e "${canon}" && true || { echo /bin/rm "./${line}"; }; done
Replace the echo commands with true for the affirmative and the echo /bin/rm command.
To actually effect the change, remove the echo in front of /bin/rm.