backup.sh: allow using different tmp dir

When backup size grows, we had cases where tar was filling up /tmp
This patch allows specifying a different tmp dir, used by tar
(through TMPDIR variable).

Example usage:
  TMPDIR=/home/user/mytempdir ./backup.sh

1 files changed, 5 insertions, 0 deletions

diff --git a/backup.sh b/backup.sh
index f4cf1de..33323b7 100755
--- a/backup.sh
+++ b/backup.sh
@@ -1,6 +1,11 @@
 #!/bin/sh
 
 BACKUP_DIR="backup-$(date +%Y%m%d_%H%M)"
+# use /tmp by default on host (this is used by tar)
+TMPDIR=${TMPDIR:-/tmp}
+export TMPDIR
+
+mkdir -p $TMPDIR
 
 mkdir $BACKUP_DIR
 cp boards.yaml $BACKUP_DIR