chore: Use grep -E / grep -F instead of egrep / fgrep (#2164)

Ensures that the -E or -F option, when used, is the first option
* i.e. grep -oE => grep -E -o

Updates _bash-it-grep to invoke grep with just the provided arguments
* This function was (and still is) unused, but decided this new functionality was actually more useful

Introduces _bash-it-fgrep to invoke grep -F

Removes type -P egrep from the _bash-it-*grep functions

For usages that were already going to be modified, use -F if appropriate
* Does not touch grep usages that may have benefited from -F, but were not otherwise considered for this PR

Adds shellcheck header to modified .bash files that didn't already have it

plugins/available/aws.plugin.bash

@@ -1,3 +1,4 @@
+# shellcheck shell=bash
 cite about-plugin
 about-plugin 'AWS helper functions'
 
@@ -40,13 +41,13 @@ function __awskeys_help {
 function __awskeys_get {
     local ln=$(grep -n "\[ *$1 *\]" "${AWS_SHARED_CREDENTIALS_FILE}" | cut -d ":" -f 1)
     if [[ -n "${ln}" ]]; then
-        tail -n +${ln} "${AWS_SHARED_CREDENTIALS_FILE}" | egrep -m 2 "aws_access_key_id|aws_secret_access_key"
-        tail -n +${ln} "${AWS_SHARED_CREDENTIALS_FILE}" | egrep -m 1 "aws_session_token"
+        tail -n +${ln} "${AWS_SHARED_CREDENTIALS_FILE}" | grep -F -m 2 -e "aws_access_key_id" -e "aws_secret_access_key"
+        tail -n +${ln} "${AWS_SHARED_CREDENTIALS_FILE}" | grep -F -m 1 "aws_session_token"
     fi
 }
 
 function __awskeys_list {
-    local credentials_list="$((egrep '^\[ *[a-zA-Z0-9_-]+ *\]$' "${AWS_SHARED_CREDENTIALS_FILE}"; grep "\[profile" "${AWS_CONFIG_FILE}" | sed "s|\[profile |\[|g") | sort | uniq)"
+    local credentials_list="$((grep -E '^\[ *[a-zA-Z0-9_-]+ *\]$' "${AWS_SHARED_CREDENTIALS_FILE}"; grep "\[profile" "${AWS_CONFIG_FILE}" | sed "s|\[profile |\[|g") | sort | uniq)"
     if [[ -n $"{credentials_list}" ]]; then
         echo -e "Available credentials profiles:\n"
         for profile in ${credentials_list}; do

plugins/available/jekyll.plugin.bash

@@ -30,8 +30,8 @@ function editpost() {
 	pushd "${SITE}/_posts" > /dev/null || return
 
 	for POST in *; do
-		DATE="$(echo "${POST}" | grep -oE "[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}")"
-		TITLE="$(grep -oE "title: (.+)" < "${POST}")"
+		DATE="$(echo "${POST}" | grep -E -o "[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}")"
+		TITLE="$(grep -E -o "title: (.+)" < "${POST}")"
 		TITLE="${TITLE/title: /}"
 		echo "${COUNTER}) 	${DATE}	${TITLE}"
 		POSTS[COUNTER]="$POST"

plugins/available/postgres.plugin.bash

@@ -1,3 +1,4 @@
+# shellcheck shell=bash
 cite about-plugin
 about-plugin 'postgres helper functions'
 
@@ -50,7 +51,7 @@ function postgres_status {
 
 
 function is_postgres_running {
-  $POSTGRES_BIN/pg_ctl -D $PGDATA status | egrep -o "no server running"
+  $POSTGRES_BIN/pg_ctl -D $PGDATA status | grep -F -o "no server running"
 }