forestbaker

http://www.kfirlavi.com/blog/2012/11/06/elegant-locking-of-bash-program/

Simple
#########################################
#!/bin/bash

# exit if flock fails.
set -e

# Wait for lock on /var/lock/.myscript.exclusivelock (fd 200) for 10 seconds

forestbaker

Complex Shell Script Outline
----------------------------
header
begin script
preamble:
 - sanity checks
 - create shell environ
 - log & debug
error handling
check dependencies

forestbaker

# for loop on directories in PATH 
for foo in ${PATH//:/ }; do

done

# use mapfile to load binaries
# just loads up element 0
mapfile _binary <${PATH//:/\/\* }

forestbaker

#!/usr/bin/env bash
# From Bash Hackers - http://wiki.bash-hackers.org/howto/collapsing_functions
# The first time you run chatter(), the function redefines itself based on the value of verbose. Thereafter, chatter doesn't check $verbose, it simply is.
# Further calls to the function reflect its collapsed nature. 
# If verbose is unset, chatter will echo nothing, with no extra effort from the developer.

[[ $1 = -v || $1 = --verbose ]] && verbose=1

chatter() {
  if [[ $verbose ]]; then

forestbaker

# # Includes perfect date perfected. The uses go beyond backups, beyond space and time ... ok not time.
# # Creates a directory structure of ./YYYY/mm/dd/HH/MM/SS
mkdir -p "$(date '+%Y/%m/%d/%H/%M/%S')"

# enDIRing elegant epoch
# # -p is optional - unless co-processing!
# # the " and ' are also optional, but "'safer'"
# # for scripting, do set the epoch in a variable, reference that variable - write once read many and yer done!
mkdir -p "$(date '+%s')"

forestbaker

# captures packets on bond0 interface containing "REGISTER" for 60 seconds
timeout 60 tshark -i bond0 -R sip.CSeq.method=="REGISTER"

# more tuning

forestbaker

# removes stuff I didn't want to read
apache2ctl status | grep -v '\.\.' | grep -v '^\"' | grep -v 'Scoreboard'

forestbaker

# original - this is all bad logins - ever!
lastb -i | grep -Po '\b(?!255)(?:\d{1,3}\.){3}(?!255)\d{1,3}\b' | sort | uniq -c | awk '{ if ($1 >= 5) print $2; }'

# early prototype - this works - but returns words
lastb -i | awk '{ print $3 }' | sort | uniq -c | awk '{ if ($1 >= 5) print $2; }'

# ah ha! this filters out the blank line and date/time stamp that was causing the words to appear
lastb -i | egrep -v '^$|btmp' | awk '{ print $3 }' | sort | uniq -c | awk '{ if ($1 >= 5) print $2; }'

forestbaker

service mysql stop
mysqld_safe --skip-grant-tables > /dev/null 2>&1 &

# wait for previous command to complete

mysql -u root -e "use mysql; update user set password=PASSWORD('NEW-PASSWORD') where user='root'; flush privileges;"
service mysql start

forestbaker

# The first method opens file.txt, writes one line, then closes file.txt.  Then repeats those three steps 100 times
# The second method opens file.txt, writes 100 lines and closes file.txt

#!/usr/bin/sh

# typical use of a while loop - 
# while $count is less than or equal to 100. 
# append the value of $count to file.txt

count=1