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a secure bash shell function to interactively set and export an environment variable
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| #!/bin/bash | |
| function set-secret { | |
| # TODO: handle signals: an ill-timed signal could leave the user | |
| # with a non-sane terminal, which can really foul things up | |
| # even for experienced users | |
| ME='set-secret' | |
| # state machine vars | |
| do_help=false | |
| export_to_env=false | |
| return_status=0 | |
| parsed_opt_count=0 | |
| while getopts 'he' option | |
| do | |
| parsed_opt_count=$(( $parsed_opt_count + 1 )) | |
| case "$option" in | |
| h) | |
| do_help=true | |
| ;; | |
| e) | |
| export_to_env=true | |
| ;; | |
| *) | |
| echo "$ME: error $option: unknown option" 1>&2 | |
| return_status=1 | |
| ;; | |
| esac | |
| done | |
| shift $parsed_opt_count | |
| if [[ $return_status != 1 ]] | |
| then | |
| if [[ $# != 1 ]] | |
| then | |
| echo "$ME: error this command expects a single argument" 1>&2 | |
| return_status=1 | |
| elif echo "$1" | grep -q -i -e '^-*help$' | |
| then | |
| do_help=true | |
| elif echo "$1" | grep -q -e '^[^a-zA-Z_]' -e '[^a-zA-Z_0-9]' | |
| then | |
| echo "$ME: error \`$1' is not a legal variable name;" 1>&2 | |
| echo "Names must match /^[a-zA-Z_][a-zA-Z_0-9]*$/" 1>&2 | |
| return_status=1 | |
| fi | |
| fi | |
| if $do_help || [[ $return_status != 0 ]] | |
| then | |
| echo "Usage: $ME VAR_NAME" | |
| echo '' | |
| echo "Shell function to set VAR_NAME while concealing its value" | |
| echo "tty echoing is set to off during value capture, so you can safely set secrets" | |
| return $return_status | |
| fi | |
| var_name="$1" | |
| stty -echo | |
| read -p "enter value for \`$var_name': " "$var_name" | |
| stty echo | |
| if $export_to_env | |
| then | |
| export "$var_name" | |
| fi | |
| } |
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