tonyc

Using strace and lsof to debug blocked processes

You can use strace on a specific pid to figure out what a specific process is doing, e.g.:

strace -fp <pid>

You might see something like:

select(9, [3 5 8], [], [], {0, 999999}) = 0 (Timeout)

benhosmer

Using the nc command you can scan a port or a range of ports to verify whether a UDP port is open and able to receive traffic.

This first command will scan all of the UDP ports from 1 to 65535 and add the results to a text file:

$ nc -vnzu server.ip.address.here 1-65535 > udp-scan-results.txt

This merely tells you that the UDP ports are open and receive traffic.

Perhaps a more revealing test would be to actually transfer a file using UDP.

muhqu

#!/bin/bash
if [ -z "$1" ]; then
  echo "Usage: sudo $0 /dev/sdh1"
  exit 1;
fi

dd if=$1 of=/dev/null & pid=$!
while true; do
  ps -p$pid --no-heading || break;
  echo "-- $(date) ------------------";

datagrok

Ideas for improvements to git log --graph

I will maybe someday get around to dusting off my C and making these changes myself unless someone else does it first.

Make the graph for --topo-order less wiggly

Imagine a long-running development branch periodically merges from master. The git log --graph --all --topo-order is not as simple as it could be, as of git version 1.7.10.4.

It doesn't seem like a big deal in this example, but when you're trying to follow the history trails in ASCII and you've got several different branches displayed at once, it gets difficult quickly.

grenade

#!/bin/bash

mkdir -p ~/.ssh

# generate new personal ed25519 ssh keys
ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519 -C "rob thijssen <[email protected]>"
ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_robtn -C "rob thijssen <[email protected]>"

# generate new host cert authority (host_ca) ed25519 ssh key
# used for signing host keys and creating host certs

rxaviers

People

:bowtie:	😄 :smile:	😆 :laughing:
😊 :blush:	😃 :smiley:	☺️ :relaxed:
😏 :smirk:	😍 :heart_eyes:	😘 :kissing_heart:
😚 :kissing_closed_eyes:	😳 :flushed:	😌 :relieved:
😆 :satisfied:	😁 :grin:	😉 :wink:
😜 :stuck_out_tongue_winking_eye:	😝 :stuck_out_tongue_closed_eyes:	😀 :grinning:
😗 :kissing:	😙 :kissing_smiling_eyes:	😛 :stuck_out_tongue:

pmorie

# Source: http://fvue.nl/wiki/Bash:_Error_handling
#
#!/bin/bash -eu
# -e: Exit immediately if a command exits with a non-zero status.
# -u: Treat unset variables as an error when substituting.
 
(false)                   # Caveat 1: If an error occurs in a subshell, it isn't detected
(false) || false          # Solution: If you want to exit, you have to detect the error yourself
(false; true) || false    # Caveat 2: The return status of the ';' separated list is `true'
(false && true) || false  # Solution: If you want to control the last command executed, use `&&'

ipbastola

Safest way to clean up boot partition - Ubuntu 14.04LTS-x64, Ubuntu 16.04LTS-x64

Reference

Case I: if /boot is not 100% full and apt is working

1. Check the current kernel version

$ uname -r 

cskeeters

#!/bin/bash

# Calculates network and broadcast based on supplied ip address and netmask

# Usage: broadcast_calc.sh 192.168.0.1 255.255.255.0
# Usage: broadcast_calc.sh 192.168.0.1/24


tonum() {
    if [[ $1 =~ ([[:digit:]]+)\.([[:digit:]]+)\.([[:digit:]]+)\.([[:digit:]]+) ]]; then

acobaugh

for key in .git-crypt/keys/default/0/* ; do gpg -k $(echo $(basename $key) | sed -e 's/.gpg//') ; done ;