Whitespace#

  • %0a: newline
  • %20: space
  • %09: tab
  • ${IFS}: Input Field Separators ↗️ (typically space, tab, newline)
  • bash bracket expansion: {ls,-la} turns into ls -la

Special characters#

  • forward slash: echo ${PATH:0:1}
  • semicolon: echo ${LS_COLORS:10:1}
  • pipe: try using <<<

Shifting characters#

This command will shift a letter one to the right echo $(tr '!-}' '"-~'<<<[). e.g. ~ becomes !.

shift_generator() {
  local shift=$1
  local char=$2
  local second_start=$((33 + shift))
  local second_end=$((33 + shift - 1))
  printf "echo \$(tr '\\!-~' '"
  printf '%b-~\\!-%b' "$(printf '\\%03o' $second_start)" "$(printf '\\%03o' $second_end)"
  printf "'<<<'%s')\n" "$char"
}

# usage
shift_generator 1 "~"

Tooling#

For more advanced obfuscation you can consider tools such as:

References#