diff --git a/completion/available/fabric.completion.bash b/completion/available/fabric.completion.bash
index 6f746454..a8984d9c 100644
--- a/completion/available/fabric.completion.bash
+++ b/completion/available/fabric.completion.bash
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 #
 # Bash completion support for Fabric (http://fabfile.org/)
 #
@@ -91,7 +91,7 @@ function __fab_completion() {
         -*)
             if [[ -z "${__FAB_COMPLETION_LONG_OPT}" ]]; then
                 export __FAB_COMPLETION_LONG_OPT=$(
-                    fab --help | egrep -o "\-\-[A-Za-z_\-]+\=?" | sort -u)
+                    fab --help | grep -E -o "\-\-[A-Za-z_\-]+\=?" | sort -u)
             fi
             opts="${__FAB_COMPLETION_LONG_OPT}"
             ;;
@@ -101,7 +101,7 @@ function __fab_completion() {
         # -*)
         #     if [[ -z "${__FAB_COMPLETION_SHORT_OPT}" ]]; then
         #         export __FAB_COMPLETION_SHORT_OPT=$(
-        #             fab --help | egrep -o "^ +\-[A-Za-z_\]" | sort -u)
+        #             fab --help | grep -E -o "^ +\-[A-Za-z_\]" | sort -u)
         #     fi
         #     opts="${__FAB_COMPLETION_SHORT_OPT}"
         #     ;;
diff --git a/completion/available/gradle.completion.bash b/completion/available/gradle.completion.bash
index 35971d50..ef9677c6 100644
--- a/completion/available/gradle.completion.bash
+++ b/completion/available/gradle.completion.bash
@@ -1,3 +1,5 @@
+# shellcheck shell=bash
+
 # Copyright (c) 2017 Eric Wendelin
 
 # Permission is hereby granted, free of charge, to any person obtaining a copy of
@@ -66,7 +68,7 @@ __gradle-generate-script-cache() {
 
     if [[ ! $(find $cache_dir/$cache_name -mmin -$cache_ttl_mins 2>/dev/null) ]]; then
         # Cache all Gradle scripts
-        local gradle_build_scripts=$(find $project_root_dir -type f -name "*.gradle" -o -name "*.gradle.kts" 2>/dev/null | egrep -v "$script_exclude_pattern")
+        local gradle_build_scripts=$(find $project_root_dir -type f -name "*.gradle" -o -name "*.gradle.kts" 2>/dev/null | grep -E -v "$script_exclude_pattern")
         printf "%s\n" "${gradle_build_scripts[@]}" > $cache_dir/$cache_name
     fi
 }
diff --git a/completion/available/makefile.completion.bash b/completion/available/makefile.completion.bash
index e72ba6fd..018586ca 100644
--- a/completion/available/makefile.completion.bash
+++ b/completion/available/makefile.completion.bash
@@ -1,3 +1,5 @@
+# shellcheck shell=bash
+
 # Bash completion for Makefile
 # Loosely adapted from http://stackoverflow.com/a/38415982/1472048
 
@@ -17,7 +19,7 @@ _makecomplete() {
   for f in "${files[@]}" ; do
     while IFS='' read -r line ; do
       targets+=("$line")
-    done < <(grep -oE '^[a-zA-Z0-9_-]+:([^=]|$)' "$f" | cut -d':' -f1)
+    done < <(grep -E -o '^[a-zA-Z0-9_-]+:([^=]|$)' "$f" | cut -d':' -f1)
   done
 
   [ "${#targets[@]}" -eq 0 ] && return 0
diff --git a/lib/helpers.bash b/lib/helpers.bash
index 2ee43a17..3675b0f2 100644
--- a/lib/helpers.bash
+++ b/lib/helpers.bash
@@ -211,7 +211,7 @@ function _is_function() {
 	_example '$ _is_function ls && echo exists'
 	_group 'lib'
 	local msg="${2:-Function '$1' does not exist}"
-	if LC_ALL=C type -t "$1" | _bash-it-egrep -q 'function'; then
+	if LC_ALL=C type -t "$1" | _bash-it-fgrep -q 'function'; then
 		return 0
 	else
 		_log_debug "$msg"
diff --git a/lib/utilities.bash b/lib/utilities.bash
index 6d5fd5d4..75e914b8 100644
--- a/lib/utilities.bash
+++ b/lib/utilities.bash
@@ -60,15 +60,21 @@ function _bash-it-array-dedup() {
 	printf '%s\n' "$@" | sort -u
 }
 
-# Outputs a full path of the grep found on the filesystem
+# Runs `grep` with *just* the provided arguments
 function _bash-it-grep() {
-	: "${BASH_IT_GREP:=$(type -P egrep || type -P grep)}"
-	printf "%s" "${BASH_IT_GREP:-/usr/bin/grep}"
+	: "${BASH_IT_GREP:=$(type -P grep)}"
+	"${BASH_IT_GREP:-/usr/bin/grep}" "$@"
 }
 
-# Runs `grep` with extended regular expressions
+# Runs `grep` with fixed-string expressions (-F)
+function _bash-it-fgrep() {
+	: "${BASH_IT_GREP:=$(type -P grep)}"
+	"${BASH_IT_GREP:-/usr/bin/grep}" -F "$@"
+}
+
+# Runs `grep` with extended regular expressions (-E)
 function _bash-it-egrep() {
-	: "${BASH_IT_GREP:=$(type -P egrep || type -P grep)}"
+	: "${BASH_IT_GREP:=$(type -P grep)}"
 	"${BASH_IT_GREP:-/usr/bin/grep}" -E "$@"
 }
 
@@ -150,12 +156,12 @@ function _bash-it-component-list-matching() {
 
 function _bash-it-component-list-enabled() {
 	local IFS=$'\n' component="$1"
-	_bash-it-component-help "${component}" | _bash-it-egrep '\[x\]' | awk '{print $1}' | sort -u
+	_bash-it-component-help "${component}" | _bash-it-fgrep '[x]' | awk '{print $1}' | sort -u
 }
 
 function _bash-it-component-list-disabled() {
 	local IFS=$'\n' component="$1"
-	_bash-it-component-help "${component}" | _bash-it-egrep -v '\[x\]' | awk '{print $1}' | sort -u
+	_bash-it-component-help "${component}" | _bash-it-fgrep -v '[x]' | awk '{print $1}' | sort -u
 }
 
 # Checks if a given item is enabled for a particular component/file-type.
diff --git a/lint_clean_files.sh b/lint_clean_files.sh
index 26650b16..cc268604 100755
--- a/lint_clean_files.sh
+++ b/lint_clean_files.sh
@@ -8,8 +8,8 @@
 # shellcheck disable=SC2002  # Prefer 'cat' for cleaner script
 mapfile -t FILES < <(
 	cat clean_files.txt \
-		| grep -v -E '^\s*$' \
-		| grep -v -E '^\s*#' \
+		| grep -E -v '^\s*$' \
+		| grep -E -v '^\s*#' \
 		| xargs -n1 -I{} find "{}" -type f
 )
 
diff --git a/plugins/available/aws.plugin.bash b/plugins/available/aws.plugin.bash
index 54a86691..14d26cae 100644
--- a/plugins/available/aws.plugin.bash
+++ b/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 ${credentials_list}; do
diff --git a/plugins/available/jekyll.plugin.bash b/plugins/available/jekyll.plugin.bash
index d818b076..3c12d826 100644
--- a/plugins/available/jekyll.plugin.bash
+++ b/plugins/available/jekyll.plugin.bash
@@ -30,8 +30,8 @@ function editpost() {
 	pushd "${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"
diff --git a/plugins/available/postgres.plugin.bash b/plugins/available/postgres.plugin.bash
index 8f239985..9f66152b 100644
--- a/plugins/available/postgres.plugin.bash
+++ b/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"
 }
 
 
diff --git a/themes/rjorgenson/rjorgenson.theme.bash b/themes/rjorgenson/rjorgenson.theme.bash
index 71d29e78..6e73c4a2 100644
--- a/themes/rjorgenson/rjorgenson.theme.bash
+++ b/themes/rjorgenson/rjorgenson.theme.bash
@@ -1,3 +1,5 @@
+# shellcheck shell=bash
+
 # port of zork theme
 
 # set colors for use throughout the prompt
@@ -50,7 +52,7 @@ function is_integer() { # helper function for todo-txt-count
 
 todo_txt_count() {
     if `hash todo.sh 2>&-`; then # is todo.sh installed
-        count=`todo.sh ls | egrep "TODO: [0-9]+ of ([0-9]+) tasks shown" | awk '{ print $4 }'`
+        count=`todo.sh ls | grep -E "TODO: [0-9]+ of ([0-9]+) tasks shown" | awk '{ print $4 }'`
         if is_integer $count; then # did we get a sane answer back
             echo "${BRACKET_COLOR}[${STRING_COLOR}T:$count${BRACKET_COLOR}]$normal"
         fi