From 60d68bbbbc76bbfdb02aeb47065800f9e5e71328 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Mah=C3=A9?= <frederic.mahe@cirad.fr>
Date: Wed, 10 Apr 2019 11:49:30 +0200
Subject: [PATCH] more compact test and operation
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- factorize file name (don't repeat yourself®),
- sed does not need `-e`:
> If no -e, --expression, -f, or --file option is given, then the first non-option argument  is taken  as  the sed script to interpret.  All remaining arguments are names of input files; if no input files are specified, then the standard input is read.
- sed does not need `g` (`^#` cannot occur multiple times on the same line),
- sed expression, use a space to separate the conditional pattern `/--dport 22 /` from the rest of the expression for clarity
---
 ssh_on.sh | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/ssh_on.sh b/ssh_on.sh
index 389503b..310e27f 100644
--- a/ssh_on.sh
+++ b/ssh_on.sh
@@ -36,11 +36,12 @@ mount | grep "on / .*[(,]ro[,$]" -q && RO_ROOT="true"
 mv /etc/init.d/_S50sshd /etc/init.d/S50sshd > /dev/null 2>&1
 sync
 [ "$RO_ROOT" == "true" ] && mount / -o remount,ro
-if [ -f /media/fat/linux/iptables.up.rules ]
-then
-	sed -e '/--dport 22 /s/^#//g' -i /media/fat/linux/iptables.up.rules
-fi
+
+# start listening port 22 (SSH)
+IP_FILTERING="/media/fat/linux/iptables.up.rules"
+[[ -f "${IP_FILTERING}" ]] && sed -i '/--dport 22 / s/^#//' "${IP_FILTERING}"
 sync
+
 if [ -f /etc/network/if-pre-up.d/iptables ]
 then
 	/etc/network/if-pre-up.d/iptables
@@ -50,4 +51,4 @@ fi
 echo "SSH is on and"
 echo "active at startup."
 echo "Done!"
-exit 0
\ No newline at end of file
+exit 0