6 # $HOME/.flag-cache <- Autogenerated flag (refreshed when hostname changes)
7 # /etc/flag <- Site admin's flag
8 # $HOME/.flag <- Local user's flag
9 # Check them in that order.
11 # Name available algos as algo_something() and left-align for autodetection
12 # Order the algos by priority: the first one that is correct will be used
13 algo_cksum_linux() { printf '%08x\n' $(cksum) | head -n 1; }
14 algo_cksum_freebsd() { printf '%08x\n' $(cksum -o 3) | head -n 1; }
15 algo_crc32() { crc32 /dev/stdin; }
16 algo_crc32sum() { crc32sum; }
17 algo_crc32sum_linux() { crc32sum-linux; }
18 algo_crc32sum_freebsd() { crc32sum-freebsd; }
19 algo_crc32_gzip() { gzip -c | tail -c 8 | od -An -N 4 -tx4 | tr -dc '0-9a-f\n'; }
20 algo_python() { python -c 'import sys; import zlib; print "%08x\n" % (zlib.crc32("".join(sys.stdin.readlines())) & 0xFFFFFFFF)'; }
21 algo_ruby() { ruby -e 'require "zlib"; printf "%08x\n", Zlib.crc32(STDIN.readlines.join)'; }
22 algo_php() { php -r 'printf("%08x\n", crc32(file_get_contents("/dev/stdin")));'; }
23 algo_perl() { perl -e 'use String::CRC32; printf("%08x\n", crc32(*STDIN));'; }
26 sed -e '/^algo_[^(]*()/!d; s/().*$//' "${0}" | while read algo
28 if [ "$(printf "meow" | "${algo}" 2>/dev/null)" = "8a106afe" ]
37 # Hash the passed string into 8 hex characters
38 [ "${crc32_algo}" ] || crc32_algo="$(find_crc32_algo)"
39 if [ -z "${crc32_algo}" ]
41 echo "No crc32 algo found!" >&2
45 printf "%s" "${*}" | "${crc32_algo}" 2>/dev/null | awk '{print $1}'
51 myhost="$(/bin/hostname -f)"
52 cache="${HOME}/.flag-cache"
55 flag_hex="$(awk '/^'${myhost}'/{print $2}' "${cache}")"
57 if [ -z "${flag_hex}" ]
59 flag_hex="$(hash_string "${myhost}")" && printf "%s\t%s\n" "${myhost}" "${flag_hex}" >> "${cache}"
64 if [ -f "${HOME}/.flag" ]
66 flag_hex="$(cat "${HOME}/.flag")"
69 if [ -z "${flag_hex}" ] && [ -f "/etc/flag" ]
71 flag_hex="$(cat "/etc/flag")"
74 if [ -z "${flag_hex}" ]
76 flag_hex="$(flagcache)"
79 # Now we definitely have flag_hex
81 char="$(printf '%c' "${data}")"
82 data="${data##${char}}"
91 echo $(( 0x${1} + 0 ))
97 echo "Usage: flag 'hexcode' [symbol] [shellmode]" >&2
98 echo "Generates an ANSI color flag using the specified hex codes" >&2
99 echo "Uses the optional symbol (or ' ') to draw the flag" >&2
100 echo "shellmode encapsulates all nonprintable codes in \[\] to" >&2
101 echo " give the shell hints on how long the string is, for proper" >&2
102 echo " wrapping of command prompts." >&2
108 [ -n "${shm}" ] && open='\\[' shut='\\]'
109 while [ -n "${data}" ]
112 ord=$(hexdec "${char}")
114 [ "$(( ${ord} & 8 ))" -gt 0 ] && bright="1;7"
115 colour="$(( ${ord} & 7 ))"
116 printf "${open}\033[%s;3%s;4%sm${shut}%s" "${bright}" "${colour}" "${colour}" "${sym:-${char}}"
118 printf "${open}\033[0m${shut}"
122 echo "Usage: $(basename "${0}") [-s #] [-e]" >&2
123 echo "Produces a neat little ansi colour 'flag' based off" >&2
124 echo " a hash of the machine's hostname (or settable via" >&2
125 echo " ~/.flag or /etc/flag) which can uniquely visually" >&2
126 echo " identify a machine, at a glance. Useful for placing" >&2
127 echo " into /etc/issue or your bash prompt, so that you" >&2
128 echo " don't send stupid commands to the wrong machine." >&2
130 echo " -s # Specify which character should be used to" >&2
131 echo " render the flag. If empty, use the hex code." >&2
132 echo " -e Turn on bash encapsulation mode, to provide" >&2
133 echo " hints to Bash on what is or is not printable" >&2
134 echo " so it can wrap your commands appropriately" >&2
135 echo " when used in your prompt" >&2
137 echo "This machine's flag is as such: ($(flag "${flag_hex}"))" >&2
147 -s) shift; symbol="${1}" ;;
148 -e) shellmode="yes" ;;
153 flag "${flag_hex}" "${symbol}" "${shellmode}"