keep the dynamism of make in pure shell
Two mechanisms, matching what the make engine actually did:
Lazy defaults. A stack setting is a function myos_default_<VAR>, called only
when the variable has no value, and called again at every reference. That is
exactly a recursive ?=: an explicit value wins, and the default follows a
DOMAIN that a .env changes later. The prefix is what makes it safe; the first
version used a bare function named after the variable, and the test suite
caught it running /usr/bin/host for a stack group called host.
Templates. myos env-update fills a .env from the .env.dist files, expanding
${VAR} against the current values and running $(command), forward references
included.
Also fixed: the project .env now wins over /etc/conf.d/myos, which is what the
documentation claimed and the code did not.
share/make/shim.mk lets a project keep make as a front end: every myos command
becomes a target that shells out to bin/myos, and the project keeps its own
targets and its stack .mk files. It sits outside make/ because the legacy
engine globs every .mk in there.
This commit is contained in:
Yann Autissier
@@ -0,0 +1,26 @@
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#shellcheck shell=sh
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# myos env-update fill the .env of the workdir from the .env.dist it finds
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#
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# Templates are read from the workdir and from every requested stack, so a
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# stack can ship the variables it expects and their defaults.
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myos_cmd_env_update() {
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_target=${ENV_FILE:-$WORKDIR/.env}
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_dists=$MYOS_ARGS
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if [ -z "$_dists" ]; then
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for _ref in $MYOS_STACKS; do
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_d=$(myos_stack_resolve "$_ref" 2>/dev/null) || continue
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for _c in "$_d/.env.dist" "$_d/$(myos_stack_name "$_ref").env.dist"; do
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[ -f "$_c" ] && _dists="${_dists:+$_dists }$_c"
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done
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done
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for _c in "$WORKDIR/.env.dist" "$WORKDIR/.env.example" "$WORKDIR/.env.sample"; do
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[ -f "$_c" ] && _dists="${_dists:+$_dists }$_c"
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done
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fi
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[ -n "$_dists" ] || { myos_warning "no .env.dist found for $MYOS_STACKS"; return 0; }
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for _dist in $_dists; do
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myos_info "env-update $_target from $_dist"
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myos_env_update "$_target" "$_dist" "$WORKDIR/.env.$ENV"
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done
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printf '%s\n' "$_target"
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}
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@@ -80,3 +80,94 @@ myos_env_export() {
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done
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return 0
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}
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# myos_expand STRING substitute ${VAR} and $(command) in STRING.
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# shellcheck disable=SC2016 # the single quotes are deliberate: these patterns
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# match the literal characters ${ and $( in the input, they are not expansions
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# This is what the make engine did when it generated a .env out of a .env.dist:
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# ${VAR} takes the current value, $(cmd) runs the command. Nothing else is
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# interpreted, so the rest of the line can hold anything.
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myos_expand() {
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_in=$1
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_guard=0
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while [ "$_guard" -lt 16 ]; do
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_guard=$((_guard + 1))
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case $_in in
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*'${'*'}'*)
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_pre=${_in%%'${'*}
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_rest=${_in#*'${'}
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_name=${_rest%%\}*}
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_post=${_rest#*\}}
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case $_name in
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''|*[!A-Za-z0-9_]*) _in="$_pre\${$_name}$_post"; break ;;
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esac
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_in="$_pre$(myos_var "$_name")$_post" ;;
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*) break ;;
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esac
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done
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_guard=0
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while [ "$_guard" -lt 16 ]; do
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_guard=$((_guard + 1))
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case $_in in
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*'$('*')'*)
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_pre=${_in%%'$('*}
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_rest=${_in#*'$('}
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_cmd=${_rest%%)*}
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_post=${_rest#*)}
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_in="$_pre$(eval "$_cmd" 2>/dev/null)$_post" ;;
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*) break ;;
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esac
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done
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printf '%s' "$_in"
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}
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# myos_env_update FILE DIST [OVER...]
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# Add to FILE every variable of DIST that is missing from it, expanded.
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# A variable that already has a value keeps it, whether it comes from the
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# environment, from FILE, or from one of the OVER files: the .env is a record
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# of the choices already made, never something that overwrites them.
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myos_env_update() {
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_file=$1; _dist=$2; shift 2
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[ -f "$_dist" ] || return 0
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[ -e "$_file" ] || : > "$_file"
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# what the overrides pin, read before anything else
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for _over in "$@"; do
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[ -f "$_over" ] || continue
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myos_dotenv_load "$_over"
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done
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# Which keys already hold a choice, made in the environment, in the .env or
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# in an override. Those are kept verbatim; everything else is a template.
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_preset=" "
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while IFS= read -r _kv; do
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[ -n "$_kv" ] || continue
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_k=${_kv%%=*}
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[ -n "$_k" ] || continue
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[ -n "$(myos_var "$_k")" ] && _preset="$_preset$_k "
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done <<EOF
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$(myos_dotenv_parse "$_dist")
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EOF
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# Make the templates themselves visible, so a line may refer to a variable
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# defined further down the file, as the make engine allowed.
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myos_dotenv_load "$_dist"
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_added=0
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while IFS= read -r _kv; do
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[ -n "$_kv" ] || continue
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_k=${_kv%%=*}
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[ -n "$_k" ] || continue
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myos_dotenv_has "$_file" "$_k" && continue
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case $_preset in
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*" $_k "*) _v=$(myos_var "$_k") ;;
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*) _v=$(myos_expand "${_kv#*=}") ;;
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esac
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printf '%s=%s\n' "$_k" "$_v" >> "$_file"
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_added=$((_added + 1))
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done <<EOF
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$(myos_dotenv_parse "$_dist")
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EOF
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[ "$_added" -gt 0 ] && myos_info "added $_added variable(s) to $_file"
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return 0
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}
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+3
-6
@@ -4,12 +4,9 @@
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# Ported from make/apps/def.mk (uri, url, urlprefix, urlprefixs, tagprefix,
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# envprefix, servicenvs). Registrator publishes the SERVICE_<port>_TAGS label
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# to consul, fabio routes on the urlprefix- tags it finds there.
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# myos_var NAME value of the variable named NAME, empty when unset
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myos_var() {
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[ -n "${1:-}" ] || return 0
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eval "printf '%s' \"\${$1:-}\""
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}
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#
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# Every lookup goes through myos_var (lib/var.sh), so a stack setting may be a
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# plain value or a lazy default, and the two behave the same here.
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# myos_uri SERVICE PORT [BASE_URI]
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# <service>.<base uri>, unless <SERVICE>_SERVICE[_<port>]_NAME overrides the prefix
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+56
@@ -0,0 +1,56 @@
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#shellcheck shell=sh
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# var: variable resolution, with the lazy defaults the make engine had.
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#
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# make gives every `VAR ?= $(call ...)` two properties at once: an explicit
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# value wins, and the default is re-evaluated at each reference, so it sees
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# whatever a .env loaded later has changed.
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#
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# The shell gets both by keeping defaults in functions: `myos_var NAME` reads
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# the variable when it has a value, and otherwise calls the function
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# `myos_default_NAME`. The prefix matters: a bare function named after the
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# variable would collide with commands on PATH, and a stack setting called
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# `host` or `test` would then run a program instead of returning a value.
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#
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# myos_default_HOST_FABIO_SERVICE_9998_TAGS() { myos_tagprefix HOST_FABIO 9998; }
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#
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# is the exact equivalent of
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#
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# HOST_FABIO_SERVICE_9998_TAGS ?= $(call tagprefix,HOST_FABIO,9998)
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MYOS_VAR_MAX_DEPTH=${MYOS_VAR_MAX_DEPTH:-32}
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# myos_var NAME the value of NAME: the variable if it has one, else the lazy
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# default, else empty.
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myos_var() {
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[ -n "${1:-}" ] || return 0
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eval "_myos_set=\${$1+yes}"
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if [ "${_myos_set:-}" = yes ]; then
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eval "printf '%s' \"\$$1\""
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return 0
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fi
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myos_var_is_lazy "$1" || return 0
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# a default written in terms of itself would loop for ever
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_myos_depth=$((${MYOS_VAR_DEPTH:-0} + 1))
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if [ "$_myos_depth" -gt "$MYOS_VAR_MAX_DEPTH" ]; then
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myos_error "variable $1 is defined in terms of itself"
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return 1
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fi
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MYOS_VAR_DEPTH=$_myos_depth "myos_default_$1"
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}
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# myos_default NAME BODY declare a lazy default from a string, for callers
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# that build the variable name at run time
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myos_default() {
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eval "myos_default_$1() { $2; }"
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}
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# myos_var_is_lazy NAME true when NAME has no value but has a lazy default
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myos_var_is_lazy() {
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eval "_myos_set=\${$1+yes}"
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[ "${_myos_set:-}" = yes ] && return 1
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# a shell function, never a command on PATH: command -v prints the name back
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# for a function and a path for a program
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_myos_fn=$(command -v "myos_default_$1" 2>/dev/null) || return 1
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[ "$_myos_fn" = "myos_default_$1" ]
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}
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