a collection of useful and useless code snippets
- snippets
- print random string
- prettify json output
- delete dead merged git branches
- search for all files with name "pattern" in current working directory
- replace strings in text file
- yes/no prompt
- find files containing keywordA
- tcp dump
- jvm java memory leak heap analysis on running server
- profile things in python
- python build/environment best practices
- list all crontabs for all users
- mac specific things
Created by gh-md-toc
< /dev/urandom tr -dc A-Za-z0-9 | head -c${1:-64};echo;
# if the above fails:
openssl rand -base64 64 | tr -dc _A-Z-a-z-0-9 && echo "" # may be less than 64 charsInstall entr, then:
find . -name '*.sh' | entr ./my-script.sh
cat file.json | python -m json.toolgit fetch --all
git up
for i in `git branch -a | grep remote | grep -v HEAD`; do git branch --track ${i#remotes/origin/} $i; done
git checkout master
echo "the following branches have been merged into the master branch and will be purged from your local machine and from the remote:"
git branch --merged | grep -v "\*" | grep -v "master" | grep -v "develop" | xargs -n 1
while true; do
read -p "Do you want to proceed? (y/n): " yn
case $yn in
[Yy]* ) break;;
[Nn]* ) echo "* You canceled; "; exit;;
* ) echo "| Please type (Y/N): ";;
esac
done
git branch --merged | grep -v "\*" | grep -v "master" | grep -v "develop" | xargs -n 1 git push --delete origin
git branch --merged | grep -v "\*" | grep -v "master" | grep -v "develop" | xargs -n 1 git branch -dfind . -name "pattern"
#!/usr/bin/python
def get_file_names(filename_expression, start_path="."):
matches = []
for root, dirnames, filenames in os.walk(start_path):
for filename in fnmatch.filter(filenames, filename_expression):
matches.append(os.path.join(root, filename))
return matches#!/usr/bin/python
def replaceValue(file, old, new):
newlines = []
with open(file,'r') as f:
for line in f.readlines():
newlines.append(line.replace(old, new))
with open(file, 'w') as f:
for line in newlines:
f.write(line)#! /usr/bin/env python
# -*- coding: utf-8 -*-
def query_yes_no(question, default="yes"):
"""Ask a yes/no question via raw_input() and return their answer.
"question" is a string that is presented to the user.
"default" is the presumed answer if the user just hits <Enter>.
It must be "yes" (the default), "no" or None (meaning
an answer is required of the user).
The "answer" return value is one of "yes" or "no".
"""
valid = {"yes":True, "y":True, "ye":True,
"no":False, "n":False}
if default == None:
prompt = " [y/n] "
elif default == "yes":
prompt = " [Y/n] "
elif default == "no":
prompt = " [y/N] "
else:
raise ValueError("invalid default answer: '%s'" % default)
while True:
sys.stdout.write(question + prompt)
choice = raw_input().lower()
if default is not None and choice == '':
return valid[default]
elif choice in valid:
return valid[choice]
else:
sys.stdout.write("Please respond with 'yes' or 'no' "\
"(or 'y' or 'n').\n") place files in text file
grep -Rl keywordA > keywordA.txt
search for lines with keywordsB and C in those files:
grep "keyword B" -- `cat keywordA.txt` | grep keywordC
see stuff on udp port 514 (e.g. rsyslogd)
# execute as root user
tcpdump -i lo udp port 514 -A see tcp stuff on port 25
tcpdump -A -i any 'port 25'
get java heap histogram
jmap -histo:live <process_id> > file.txt
full dump
jmap -dump:format=b,file=dump.hprof <process_id>
if oracle java: e.g. force garbage collection, see
jcmd <process_id> help
see https://docs.python.org/2/library/profile.html
see https://moshez.wordpress.com/2016/01/27/learning-python-the-ecosystem/
for user in $(cut -f1 -d: /etc/passwd); do echo "crons for $user:"; crontab -u $user -l 2>/dev/null | grep -v '^#'; done
(http://stackoverflow.com/questions/134906/how-do-i-list-all-cron-jobs-for-all-users)
(code taken from: http://blog.backslasher.net/cookbook-versioning.html)
#!/usr/bin/env ruby
target_branch='master'
has_minor=`git log #{target_branch}.. --grep=BUMP_MINOR`.length > 0
has_major=`git log #{target_branch}.. --grep=BUMP_MAJOR`.length > 0
bump_type=if has_major then 'major'
elsif has_minor then 'minor'
else 'build'
end
# Get next version
split_options=['major','minor','build']
split_index=split_options.index(bump_type)
raise 'unknown bump modifier' if split_index.nil?
metadata_file='./metadata.rb'
metadata=File.read(metadata_file)
version_line=metadata.split("\n").select{|s|s[/^\s*version\W/]}.last
version_regex=/("|')([\d\.]+)("|')/
version=version_line[version_regex,2]
v_arr=version.split('.')
v_arr[split_index]=(v_arr[split_index].to_i+1).to_s
(split_index+1..v_arr.length-1).each{|a|v_arr[a]=0} # Zero other cells
new_version=v_arr.join('.')
# Read file
metadata_file='./metadata.rb'
metadata=File.read(metadata_file)
# Find version line
version_regex=/("|')([\d\.]+)("|')/
version_line=metadata.split("\n").select{|s|s[/^\s*version\W/]}.last
# Generate new one
new_version_line=version_line.gsub(version_regex,"'#{new_version}'")
new_metadata=metadata.gsub("\n#{version_line}\n","\n#{new_version_line}\n")
# Write back to file
File.write(metadata_file,new_metadata)
[alias]
lg = log --graph --decorate --pretty=format:'%C(blue)%h%Creset -%C(red)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit --date=relative
(taken from https://github.com/wmalik/dotfiles)
Which program uses how much bandwidth?
sudo nethogs
see http://www.binarytides.com/linux-commands-monitor-network/ for a list of alternatives.