From ce80a3b6acafbab6aad65b49598c90e75078802a Mon Sep 17 00:00:00 2001
From: Hari Sekhon <harisekhon@gmail.com>
Date: Sat, 15 Aug 2020 13:48:53 +0100
Subject: [PATCH] added grep_or_append.sh

---
 grep_or_append.sh | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100755 grep_or_append.sh

diff --git a/grep_or_append.sh b/grep_or_append.sh
new file mode 100755
index 00000000..778387fe
--- /dev/null
+++ b/grep_or_append.sh
@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+#  vim:ts=4:sts=4:sw=4:et
+#
+#  Author: Hari Sekhon
+#  Date: 2020-08-15 12:55:07 +0100 (Sat, 15 Aug 2020)
+#
+#  https://github.com/harisekhon/bash-tools
+#
+#  License: see accompanying Hari Sekhon LICENSE file
+#
+#  If you're using my code you're welcome to connect with me on LinkedIn and optionally send me feedback to help steer this or other code I publish
+#
+#  https://www.linkedin.com/in/harisekhon
+#
+
+set -euo pipefail
+[ -n "${DEBUG:-}" ] && set -x
+srcdir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# shellcheck disable=SC1090
+. "$srcdir/lib/utils.sh"
+
+# shellcheck disable=SC2034,SC2154
+usage_description="
+For each line passed in via standard input, checks the given file argument and appends each line that doesn't already exist within the file
+
+This is re-evaluated for each line, so acts as a 'uniq' filter for input lines too
+
+See vagrant/provision.sh for an example of this in use
+"
+
+# used by usage() in lib/utils.sh
+# shellcheck disable=SC2034
+usage_args="<filename>"
+
+help_usage "$@"
+
+min_args 1 "$@"
+
+filename="$1"
+
+while read -r line; do
+    # if file doesn't exist will append to create it
+    grep -Fxq "$line" "$filename" 2>/dev/null ||
+    echo "$line" >> "$filename"
+done