Don't blindly run editable github gist with bash

home/.config/shell/aliases

@@ -217,7 +217,6 @@ alias path='echo -e ${PATH//:/\\n}' # Print each PATH entry on a separate line
 alias unsudo='sudo -k' # Reset sudo timeout (sudo will require password)
 alias vimwiki='vim -c VimwikiIndex' # Open vimwiki index
 alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
-alias colors-256='curl -s https://gist.githubusercontent.com/HaleTom/89ffe32783f89f403bba96bd7bcd1263/raw/ | bash' # Show color table
 alias tty-clock='tty-clock -Ssc' # Terminal clock screensaver
 alias rick='curl -s -L https://raw.githubusercontent.com/ItsDrike/rickrollrc/master/roll.sh| bash' # Terminal rickroll
 

home/.local/bin/scripts/colors-256

@@ -0,0 +1,102 @@
+#!/bin/bash
+
+# # Print out 256 colors, with each number printed in its corresponding colour
+#
+# This file is uploaded on <https://gist.githubusercontent.com/HaleTom/89ffe32783f89f403bba96bd7bcd1263/raw/>
+# It was originally intended to be used as an alias that curled this URL and piped it into bash, however
+# this is very unsafe as the owner can change the content of this gist at his convenience, meaning it was
+# a potential security vulnerability. This is a script version of this alias to avoid this issue.
+#
+# The copyright for this file belongs to the original author: Tom Hale, 2016
+# This file was released under MIT license
+
+set -eu # Fail on errors or undeclared variables
+
+printable_colours=256
+
+# Return a colour that contrasts with the given colour
+# Bash only does integer division, so keep it integral
+function contrast_colour {
+    local r g b luminance
+    colour="$1"
+
+    if (( colour < 16 )); then # Initial 16 ANSI colours
+        (( colour == 0 )) && printf "15" || printf "0"
+        return
+    fi
+
+    # Greyscale # rgb_R = rgb_G = rgb_B = (number - 232) * 10 + 8
+    if (( colour > 231 )); then # Greyscale ramp
+        (( colour < 244 )) && printf "15" || printf "0"
+        return
+    fi
+
+    # All other colours:
+    # 6x6x6 colour cube = 16 + 36*R + 6*G + B  # Where RGB are [0..5]
+    # See http://stackoverflow.com/a/27165165/5353461
+
+    # r=$(( (colour-16) / 36 ))
+    g=$(( ((colour-16) % 36) / 6 ))
+    # b=$(( (colour-16) % 6 ))
+
+    # If luminance is bright, print number in black, white otherwise.
+    # Green contributes 587/1000 to human perceived luminance - ITU R-REC-BT.601
+    (( g > 2)) && printf "0" || printf "15"
+    return
+
+    # Uncomment the below for more precise luminance calculations
+
+    # # Calculate percieved brightness
+    # # See https://www.w3.org/TR/AERT#color-contrast
+    # # and http://www.itu.int/rec/R-REC-BT.601
+    # # Luminance is in range 0..5000 as each value is 0..5
+    # luminance=$(( (r * 299) + (g * 587) + (b * 114) ))
+    # (( $luminance > 2500 )) && printf "0" || printf "15"
+}
+
+# Print a coloured block with the number of that colour
+function print_colour {
+    local colour="$1" contrast
+    contrast=$(contrast_colour "$1")
+    printf "\e[48;5;%sm" "$colour"                # Start block of colour
+    printf "\e[38;5;%sm%3d" "$contrast" "$colour" # In contrast, print number
+    printf "\e[0m "                               # Reset colour
+}
+
+# Starting at $1, print a run of $2 colours
+function print_run {
+    local i
+    for (( i = "$1"; i < "$1" + "$2" && i < printable_colours; i++ )) do
+        print_colour "$i"
+    done
+    printf "  "
+}
+
+# Print blocks of colours
+function print_blocks {
+    local start="$1" i
+    local end="$2" # inclusive
+    local block_cols="$3"
+    local block_rows="$4"
+    local blocks_per_line="$5"
+    local block_length=$((block_cols * block_rows))
+
+    # Print sets of blocks
+    for (( i = start; i <= end; i += (blocks_per_line-1) * block_length )) do
+        printf "\n" # Space before each set of blocks
+        # For each block row
+        for (( row = 0; row < block_rows; row++ )) do
+            # Print block columns for all blocks on the line
+            for (( block = 0; block < blocks_per_line; block++ )) do
+                print_run $(( i + (block * block_length) )) "$block_cols"
+            done
+            (( i += block_cols )) # Prepare to print the next row
+            printf "\n"
+        done
+    done
+}
+
+print_run 0 16 # The first 16 colours are spread over the whole spectrum
+printf "\n"
+print_blocks 16 231 6 6 3 # 6x6x6 colour cube between 16 and 231 inclusive
+print_blocks 232 255 12 2 1 # Not 50, but 24 Shades of Grey