grep self ignore

Associative Arrays and how to iterate over them

bash/README.md

@@ -1,9 +1,27 @@
 # Useful BASH snippets.
 
+## Useful References
+
+https://devhints.io/bash  
+https://sharats.me/posts/shell-script-best-practices/ - awesome template of Good Things (TM) ...  
+... which then leads to https://news.ycombinator.com/item?id=33354286 - I need to read and consume this properly, so many interesting tool and usage suggestions.
+
+## one_liners.bash
+
+Collection of simple tricks not big enough to need a separate file.
+
 ## argument_parsing.bash
 
 Handling command line argument / parameter parsing at the beginning of a script.
 
+## array_append.bash
+
+How to declare an array, append new elements, iterate over the array for processing.
+
+## associative_array.bash
+
+Numerical arrays are referenced using integers, and associative are referenced using strings. Associative Arrays can be handy when you want the key to have meaning. 
+
 ## booleans.bash
 
 BASH doesn't actually have booleans, but there's tricks to make variables behave enough like bools to be useful.
@@ -24,6 +42,10 @@ Quick and easy script runtime output.
 
 tmux wrapper for another script, e.g. to have top running in part of your terminal while another task runs in the button, then nicely clean up afterwards.
 
+## tput_colours_etc.bash
+
+Using tput command to modify visual output, for example text colours.
+
 ## usage_help.bash
 
 Put your usage output in a function to make it easily callable from multiple places as required.

bash/array_append.bash

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+# Declare a string array
+arrVar=("AC" "TV" "Mobile" "Fridge" "Oven" "Blender")
+
+# Add new element at the end of the array
+arrVar+=("Dish Washer")
+
+# Iterate the loop to read and print each array element
+for value in "${arrVar[@]}"
+do
+     echo $value
+done

bash/associative_array.bash

@@ -0,0 +1,41 @@
+#!/bin/bash
+#
+# associative_array.bash. Derived from:
+# https://stackoverflow.com/questions/3112687/how-to-iterate-over-associative-arrays-in-bash
+
+# Make an array and stuff it full of values
+declare -A array
+array[repo_one]=true
+array[repo_two]=true
+array[repo_three]=false
+
+# The key is accessed using the exclamation point
+for i in "${!array[@]}"
+do
+  echo "key: $i"
+  if ${array[$i]}; then
+    echo "$i is true"
+  fi
+done
+
+# Output will be:
+#
+# key: repo_one
+# repo_one is true
+# key: repo_two
+# repo_one is true
+# key: repo_three
+
+# NOTE: Be care of -A versus -a in the array declaration. A -a makes an *indexed* array as opposed to an *associative* array.
+#       But given that an associative array is actually a hash table, it doesn't store the pairs in the order you put them
+#       into the array, they are instead stored in their hash value order. If order matters you need to use an indexed array.
+# The following shows how to use both an indexed array and an associative array together to get both, if that's what you need.
+# (Ref https://stackoverflow.com/questions/29161323/how-to-keep-associative-array-order)
+declare -a arrOrder       ; declare -A arrData
+arrOrder+=( repo_one )    ; arrData[repo_one]=true
+arrOrder+=( repo_two )    ; arrData[repo_two]=true
+arrOrder+=( repo_three )  ; arrData[repo_three]=false
+for i in "${arrOrder[@]}"
+do
+    echo "$i: ${arrData[$i]}"
+done

bash/internal_output_tee.bash

@@ -1,8 +1,15 @@
 #!/bin/bash
 
-LOGFILE="/my/log/file.log"
-exec > >(tee "$LOGFILE") 2>&1
 # This will tee both stout and sterr to terminal and logfile for the entirity of the script.
 # Useful if you cannot / don't want to wrap the script execution in a redirect at call time.
 # Stops you having to put '...| tee $LOGFILE 2>&1' on every other line of your script.
-#
+LOGFILE="/my/log/file.log"
+exec > >(tee "$LOGFILE") 2>&1
+
+# If you have tput colouring, etc, in your scripts for pretty terminal output, then the following
+# version of the above will strip the control codes so they don't pollute the log file. Not required
+# if you'll always be looking at the log file with a smart enough viewer, but this isn't always the
+# case, or you might want additional machine parsing of logs.
+exec > >(tee >(sed -r "s/\x1b\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g" | sed "s/\x0f//g" > $BUILDLOG)) 2>&1
+# First sed removes the setaf colour codes, second sed is required because despite all other attempts
+# there remains a leftover code from sgr0 resets.

bash/one_liners.bash

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+# How to strip leading "./" in "find"
+find -type f -printf '%P\n'
+  # From find manual: %P File's name with the name of the command line argument under which it was found removed.
+
+# Get a grep command to not find itself
+<command> | grep '[p]attern'
+  # will find instances of 'pattern' in the output of <command> but not the grep command itself.
+  # Ref: https://stackoverflow.com/questions/20528894/how-does-ps-aux-grep-pattern-exclude-grep-itself
+  # The pattern "[p]attern" will not match the literal string "[p]attern". Instead it will match strings
+  #   with exactly one char from the 1-character class "[p]", followed by "attern".

bash/tmux_launcher.bash

@@ -11,8 +11,19 @@ tmux attach -t sessionname                                  # jump into the acti
 tmux send-keys -t sessionname:0.0 'q' 'C-m'                 # tell 'top' in top pane to quit (C-m probably not needed here...)
 tmux kill-session -t sessionname                            # close tmux session
 
+
 # NOTE: need the following at the end of 'script.bs' to make it drop out, first two lines are optional but a good way to hold
 #       the session open until user is ready to close it, last line is the kick back to this higher level tmux wrapper.
+#
 # echo "Press any key to close the window."
 # read -s -n1
 # tmux detach
+#
+# If you can also call script.bs NOT from the tmux wrapper, then only do the above if you're actually insidie a tmux.
+# This works because tmux handily sets the TMUX variable so you can trivially check.
+#
+# if [ "$TMUX" ]; then
+#   echo "Press any key to close the window."
+#   read -s -n1
+#   tmux detach
+# fi  

bash/tput_colours_etc.bash

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+# foreground color using ANSI escape
+
+fgBlack=$(tput setaf 0) # black
+fgRed=$(tput setaf 1) # red
+fgGreen=$(tput setaf 2) # green
+fgYellow=$(tput setaf 3) # yellow
+fgBlue=$(tput setaf 4) # blue
+fgMagenta=$(tput setaf 5) # magenta
+fgCyan=$(tput setaf 6) # cyan
+fgWhite=$(tput setaf 7) # white
+
+txReset=$(tput sgr0)   # reset attributes
+
+imma_variable="bar"
+
+# Example 1: Output Foobar, with empty line before and after, in blue using echo.
+echo -e  "\n${fgBlue}Foo${imma_variable}${txReset}"
+
+# Example 2: Output Foobar, with empty line before and after, in red using printf.
+printf '\n%s%s%s%s\n\n' ${fgRed} 'Foo' ${imma_variable} ${txReset}  # need extra newline as printf doesn't give one by default
+
+# Example 3: Set output for multiple lines, then reset after you're done, i.e. not embedded in single output.
+echo -en "${fgCyan}"    # set your colour, without a newline
+echo "foobar2"          # output
+echo "foobar3"          # multiple
+echo $imma_variable     # things
+echo -en "${txReset}"   # and finally reset
+
+
+# Some other settings I haven't tested - stole straight off Teh Intewebs
+
+# background color using ANSI escape
+
+bgBlack=$(tput setab 0) # black
+bgRed=$(tput setab 1) # red
+bgGreen=$(tput setab 2) # green
+bgYellow=$(tput setab 3) # yellow
+bgBlue=$(tput setab 4) # blue
+bgMagenta=$(tput setab 5) # magenta
+bgCyan=$(tput setab 6) # cyan
+bgWhite=$(tput setab 7) # white
+
+# text editing options
+
+txBold=$(tput bold)   # bold
+txHalf=$(tput dim)    # half-bright
+txUnderline=$(tput smul)   # underline
+txEndUnder=$(tput rmul)   # exit underline
+txReverse=$(tput rev)    # reverse
+txStandout=$(tput smso)   # standout
+txEndStand=$(tput rmso)   # exit standout

excel/network_ip_masks

@@ -0,0 +1,87 @@
+A1 = IP address
+B1 = CIDR netmask
+
+ref https://gist.github.com/f-steff/d2ef30bed5328f0e417d635d3b46e256
+
+
+Calculate netmask:
+==================
+
+=bin2dec(mid(REPT("1",B1)&rept("0",32-B1),1,8))&"."&
+bin2dec(mid(REPT("1",B1)&rept("0",32-B1),9,8))&"."&
+bin2dec(mid(REPT("1",B1)&rept("0",32-B1),17,8))&"."&
+bin2dec(mid(REPT("1",B1)&rept("0",32-B1),25,8))
+
+
+Calculate start of IP range (i.e. 'network' address, FIRST HOST is +1 from this):
+=================================================================================
+
+=BITAND( 
+  (LEFT(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160)))-1))
+  ,
+  (bin2dec(mid(REPT("1",B1)&rept("0",32-B1),1,8))) 
+)
+&"."&
+BITAND( 
+  (MID(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160),1))+1,find(char(160),SUBSTITUTE(A1,".",CHAR(160),2))-find(char(160),SUBSTITUTE(A1,".",CHAR(160),1))-1))
+  ,
+  (bin2dec(mid(REPT("1",B1)&rept("0",32-B1),9,8)) )
+)
+&"."&
+BITAND(
+  (MID(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160),2))+1,find(char(160),SUBSTITUTE(A1,".",CHAR(160),3))-find(char(160),SUBSTITUTE(A1,".",CHAR(160),2))-1))
+  ,
+  (bin2dec(mid(REPT("1",B1)&rept("0",32-B1),17,8)))
+)
+&"."&
+BITAND(
+  (MID(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160),3))+1,len(A2)-find(char(160),SUBSTITUTE(A1,".",CHAR(160),3))))
+  ,
+  bin2dec(mid(REPT("1",B1)&rept("0",32-B1),25,8))
+)
+
+
+Calculate end of IP range (i.e. 'broadcast' address, LAST HOST is -1 from this):
+================================================================================
+
+=BITOR( 
+  (LEFT(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160)))-1))
+  ,
+  (255-bin2dec(mid(REPT("1",B1)&rept("0",32-B1),1,8))) 
+)
+&"."&
+BITOR( 
+  (MID(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160),1))+1,find(char(160),SUBSTITUTE(A1,".",CHAR(160),2))-find(char(160),SUBSTITUTE(A1,".",CHAR(160),1))-1))
+  ,
+  (255-bin2dec(mid(REPT("1",B1)&rept("0",32-B1),9,8)) )
+)
+&"."&
+BITOR(
+  (MID(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160),2))+1,find(char(160),SUBSTITUTE(A1,".",CHAR(160),3))-find(char(160),SUBSTITUTE(A1,".",CHAR(160),2))-1))
+  ,
+  (255-bin2dec(mid(REPT("1",B1)&rept("0",32-B1),17,8)))
+)
+&"."&
+BITOR(
+  (MID(A1, find(char(160),SUBSTITUTE(A1,".",CHAR(160),3))+1,len(A2)-find(char(160),SUBSTITUTE(A1,".",CHAR(160),3))))
+  ,
+  255-bin2dec(mid(REPT("1",B1)&rept("0",32-B1),25,8))
+)
+
+
+
+Calculate number of hosts:
+==========================
+
+=2^(32-B1)-1
+
+
+===================================================================================================================================
+(Does not follow on from above columns.)
+===================================================================================================================================
+
+Convert traditional netmask in A1 to CIDR:
+
+="/"&32-LEN(SUBSTITUTE(TEXT(DEC2BIN(MID(A1,1,FIND(".",A1)-1)),"00000000")&TEXT(DEC2BIN(MID(A1,1+FIND(".",A1),FIND(".",A1,FIND(".",A1)+1)-FIND(".",A1)-1)),"00000000")&TEXT(DEC2BIN(MID(A1,1+FIND(".",A1,FIND(".",A1)+1),FIND(".",A1,FIND(".",A1,FIND(".",A1)+1)+1)-FIND(".",A1,FIND(".",A1)+1)-1)),"00000000")&TEXT(DEC2BIN(RIGHT(A1,LEN(A1)-FIND(".",A1,FIND(".",A1,FIND(".",A1)+1)+1))),"00000000"),"1",""))
+
+(ref https://www.reddit.com/r/excel/comments/9ivaal/simple_formula_ip_subnet_masks_to_cidr/)

excel/sexy_currency_formatting

@@ -0,0 +1,3 @@
+[>=1000000]$#.0,,"M";[>=1000]$#,##0,"k";0
+
+Enter the above as Custom Cell Formatting to get pretty output (BOE style) such as "$1.9M" or "$38k" instead of big integers.

tmux/input_sync

@@ -0,0 +1,15 @@
+# Example of a function you could place in .bashrc (or similar) showing synchronised input to multiple panes in tmux.
+
+function multi_ssh
+{
+    tmux new-session \; \
+        split-window -h \; \
+        select-pane -t 0 \; \
+        send-keys 'ssh user1@server1' C-m \; \
+        select-pane -t 1 \; \
+        send-keys 'ssh user2@server2' C-m \; \
+        setw synchronize-panes \;
+}
+
+# This will give two panes, each one ssh'd into a different server (we've assumed keys setup for auth), and with anything
+#  you now type being entered into BOTH panes simultaneously.