From 3db1c62d22b8659ad0cdbbae561e07f63abf0162 Mon Sep 17 00:00:00 2001 From: Luca BRUNO Date: Thu, 16 Apr 2020 13:28:18 +0000 Subject: [PATCH] man/systemd-service: clarify env variable expansion This clarifies some more aspects of `${FOO}` expansions in service units, mostly trying to answer my own doubts about what happens when the matching variable is not defined. --- man/systemd.service.xml | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/man/systemd.service.xml b/man/systemd.service.xml index 02eb706789..9f99feaef0 100644 --- a/man/systemd.service.xml +++ b/man/systemd.service.xml @@ -1106,10 +1106,10 @@ Basic environment variable substitution is supported. Use ${FOO} as part of a word, or as a word of its - own, on the command line, in which case it will be replaced by the - value of the environment variable including all whitespace it - contains, resulting in a single argument. Use - $FOO as a separate word on the command line, in + own, on the command line, in which case it will be erased and replaced + by the exact value of the environment variable (if any) including all + whitespace it contains, always resulting in exactly a single argument. + Use $FOO as a separate word on the command line, in which case it will be replaced by the value of the environment variable split at whitespace, resulting in zero or more arguments. For this type of expansion, quotes are respected when splitting