[PATCH] checkupdates: use $UID instead of $USER in temporary directory path

[nl6720]

If $USER is not set when running checkupdates, the temporary directory's
name will be "checkup-db-". This will cause issues if multiple users run
checkupdates. A common situation where $USER is not set is when a command
is executed with systemd-run, e.g. from a systemd unit.
See https://github.com/systemd/systemd/pull/8227 for details.

Replace the usage of $USER with $UID since it is guaranteed to exist and so
that the temporary directory is isolated per-user.

Signed-off-by: nl6720 <nl6720 at gmail.com>
---
 src/checkupdates.sh.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/checkupdates.sh.in b/src/checkupdates.sh.in
index 52f8899..ba9b960 100644
--- a/src/checkupdates.sh.in
+++ b/src/checkupdates.sh.in
@@ -85,7 +85,7 @@ if ! type -P fakeroot >/dev/null; then
 fi
 
 if [[ -z $CHECKUPDATES_DB ]]; then
-	CHECKUPDATES_DB="${TMPDIR:-/tmp}/checkup-db-${USER}/"
+	CHECKUPDATES_DB="${TMPDIR:-/tmp}/checkup-db-${UID}/"
 fi
 
 trap 'rm -f $CHECKUPDATES_DB/db.lck' INT TERM EXIT
-- 
2.24.0