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|
#!/bin/bash
#
# Synopsis:
#
# #!/bin/bash
# . export-json.bash
# export_JSON <variables>
#
# Example:
#
# $ (
# source export-json.bash &&
# export_JSON SSH_TTY \
# SSH_CONNECTION \
# SSH_CLIENT \
# SSH_AUTH_SOCK
# )
#
# {
# "SSH_TTY": "/dev/pts/0",
# "SSH_CONNECTION": "192.0.2.140 41564 198.51.100.25 22",
# "SSH_CLIENT": "192.0.2.140 41564 22",
# "SSH_AUTH_SOCK": "/tmp/ssh-XXXXcePKJl/agent.36326"
# }
#
# This bash function exports shell variables as
# JSON ("javascript object notation") strings.
#
# The string is printed to stdout.
#
# JSON is a format that represents data as
# Javascript source code so modern programmers
# can read it unlike bash source code.
#
# Variable names are given to the function as its
# argument list:
#
# $ source export-json.bash &&
# export_JSON PATH
#
# The output is a single JSON object containing
# key-value mappings between JSON strings:
#
# {
# "PATH": "/usr/local/sbin:[...]"
# }
#
# It is possible to use a different name for the
# variable in the JSON object key field than in
# the shell environment, like this:
#
# $ export_JSON DBUS_SESSION_BUS_ADDRESS=p
# {
# "p": "unix:path=/run/user/1000/bus"
# }
#
# It uses the external tool "jq" to parse string
# values placed in jq's argument list by bash and
# then encode them as JSON string values. This
# is no accidental dependency. The jq program is
# the foundation of the trustworthiness of this
# code. If we were encoding JSON strings in bash
# we would have to be a lot more careful.
arg1_to_env0()
{
case "$1" in
*[^a-zA-Z0-9_=]* | *=*=* )
echo "Error: invalid variable: '$1'" >&2
return 10
;;
[a-zA-Z_]* )
set -- "${1#*=}" "${1%%=*}"
;;
* )
echo "Error: invalid variable: '$1'" >&2
return 20
;;
esac
if [ -v "$2" ]
then
printf '%s=%s\0' "$1" "${!2}"
else
echo "Warning: ignoring unset variable: '$2'" >&2
fi
}
export_to_env0()
{
while [ $# -gt 0 ]
do
arg1_to_env0 "$1" || return
shift
done
}
to_JSON_all()
{
(
if [ "$1" = '-a' ]
then
jq_env
fi
set -- $(compgen -A arrayvar)
while [ $# -gt 0 ]
do
to_JSON "$1"
shift
done
) |
jq -s 'add'
}
to_JSON()
{
case "$1" in
-A | -a )
to_JSON_all "$@"
return
;;
esac
[ $# = 1 ] || return
case "${!1@a}" in
*a* )
(
eval "set -- \"\$1\" --args \"\${${1}[@]}\"" &&
jq -n '{ ($k): $ARGS.positional }' \
--arg k "$@"
)
;;
*A* )
(
eval 'set -- --arg k "'${1}'" --args \
"${!'${1}'[@]}" \
"${'${1}'[@]}"'
if [ $# -gt 4 ]
then
jq -n "{ (\$k): $(jq_zip2) }" "$@"
else
jq -n '{ ($k): {} }' "$@"
fi
)
;;
* )
[ -v "$1" ] &&
jq -n '{ ($k): $v }' --arg k "$1" --arg v "${!1}"
;;
esac
}
jq_zip2()
{
cat <<'END'
$ARGS.positional |
[
.[ : length/2 ],
.[ length/2 : ]
] |
transpose |
map ({ (.[0]): .[1] }) |
add
END
}
env0_to_JSON()
{
set --
while read -d ''
do
set -- "$@" --arg "${REPLY%%=*}" "${REPLY#*=}"
done
jq -n -r '$ARGS.named' "$@"
}
export_JSON_unsafe()
{
(
set -o pipefail
export_to_env0 "$@" | env0_to_JSON
)
}
safety_pipe()
{
[ $# -ge 2 ] || return
set -- "$(mktemp)" "$@" || return
if (shift 2; "$@") > "$1"
then
"$2" < "$1"
else
return $?
fi
}
export_JSON()
{
safety_pipe env0_to_JSON export_to_env0 "$@"
}
filter_vars()
{
while read
do
if [ -v "$REPLY" ]
then
printf '%s\n' "$REPLY"
fi
done
}
jq_env()
{
export_JSON $(compgen -v | filter_vars) | jq "$@"
}
jq_exports()
{
export_JSON $(compgen -e | filter_vars) | jq "$@"
}
try()
{
"$@"
printf '(Exit %s) <- [%s]\n' "$?" "${*@Q}" >&2
}
runtest()
{
set -- SSH_CLIENT SSH_TTY SSH_AUTH_SOCK SSH_CONNECTION
try export_JSON "$@"
unset unsetvar
try export_JSON SSH_TTY unsetvar
try export_JSON unsetvar SSH_TTY
try export_JSON
try export_JSON ''
try export_JSON 'invalid!' SSH_TTY
try export_JSON SSH_TTY 'invalid!'
try jq_env .unsetvar
emptyvar= try jq_env .emptyvar
try jq_exports '.|{TERM,LANG,HOSTTYPE,EDITOR,SHELL}'
try jq_env '.|{TERM,LANG,HOSTTYPE,EDITOR,SHELL}'
try to_JSON PATH BASH_ARGV BASH_VERSINFO BASH_ALIASES BASH_CMDS
}
|
