Veruse/Redirect Checker

redirect-checker.sh · 5.9 KiB · Bash Raw

#!/usr/bin/env bash
#
# check_redirects.sh - Follow and report HTTP redirect chains (max 10 hops).
#
# Run straight from a gist (it will ask for the URLs):
#   bash <(curl -fsSL https://gist.veru.se/Veruse/87653b8402024210986ecec3c826e1b9/raw/HEAD/redirect-checker.sh)
#   curl -fsSL https://gist.veru.se/Veruse/87653b8402024210986ecec3c826e1b9/raw/HEAD/redirect-checker.sh | bash
#
# Arguments/flags work if you want to skip the prompts:
#   bash <(curl -fsSL URL) https://a.com https://b.com
#   bash <(curl -fsSL URL) -f urls.txt

set -uo pipefail

MAX_REDIRECTS=10
TIMEOUT=10
CSV=0
URL_FILE=""
USER_AGENT="Mozilla/5.0 (redirect-checker)"

if [[ -t 1 ]]; then
  RED=$'\e[31m'; GREEN=$'\e[32m'; YELLOW=$'\e[33m'; CYAN=$'\e[36m'; BOLD=$'\e[1m'; RESET=$'\e[0m'
else
  RED=""; GREEN=""; YELLOW=""; CYAN=""; BOLD=""; RESET=""
fi

usage() {
  cat <<'EOF'
Usage: check_redirects.sh [options] [url ...]
  (no URLs given = interactive prompts)

Options:
  -f FILE   Read URLs from FILE (one per line, # comments and blank lines ignored)
  -m N      Max redirects to follow (default: 10)
  -t SECS   Timeout per request in seconds (default: 10)
  -c        Output CSV (url,final_url,final_status,hops,result)
  -h        Show help
EOF
  exit "${1:-0}"
}

while getopts ":f:m:t:ch" opt; do
  case "$opt" in
    f) URL_FILE="$OPTARG" ;;
    m) MAX_REDIRECTS="$OPTARG" ;;
    t) TIMEOUT="$OPTARG" ;;
    c) CSV=1 ;;
    h) usage 0 ;;
    :) echo "Option -$OPTARG requires an argument." >&2; usage 1 ;;
    \?) echo "Unknown option: -$OPTARG" >&2; usage 1 ;;
  esac
done
shift $((OPTIND - 1))

command -v curl >/dev/null 2>&1 || { echo "Error: curl is required." >&2; exit 1; }

# ---- Collect URLs ----
URLS=()
if [[ -n "$URL_FILE" ]]; then
  [[ -r "$URL_FILE" ]] || { echo "Error: cannot read $URL_FILE" >&2; exit 1; }
  while IFS= read -r line || [[ -n "$line" ]]; do URLS+=("$line"); done < "$URL_FILE"
fi
URLS+=("$@")

# ---- Interactive prompts (read from the terminal, so it works with curl | bash) ----
TTY="${TTY_DEVICE:-/dev/tty}"
if [[ ${#URLS[@]} -eq 0 ]]; then
  if ! { exec 3<"$TTY"; } 2>/dev/null; then
    echo "Error: no URLs given and no terminal available to ask for them." >&2
    usage 1
  fi

echo "${BOLD}Redirect checker${RESET} (max $MAX_REDIRECTS redirects per URL)"
  echo "  1) Check a single URL"
  echo "  2) Paste a list of URLs"
  echo "  3) Load URLs from a file"
  read -r -u 3 -p "Choose [1-3]: " choice

case "$choice" in
    1)
      read -r -u 3 -p "URL: " line
      URLS+=("$line")
      ;;
    2)
      echo "Paste URLs, one per line. Press Enter on an empty line when done:"
      while IFS= read -r -u 3 line; do
        line="${line//$'\r'/}"
        [[ -z "${line// /}" ]] && break
        URLS+=("$line")
      done
      ;;
    3)
      read -r -u 3 -p "File path: " URL_FILE
      URL_FILE="${URL_FILE/#\~/$HOME}"
      [[ -r "$URL_FILE" ]] || { echo "Error: cannot read $URL_FILE" >&2; exit 1; }
      while IFS= read -r line || [[ -n "$line" ]]; do URLS+=("$line"); done < "$URL_FILE"
      ;;
    *)
      echo "Invalid choice." >&2; exit 1 ;;
  esac

read -r -u 3 -p "Save results as CSV instead of on-screen output? [y/N]: " ans
  if [[ "$ans" =~ ^[Yy] ]]; then
    read -r -u 3 -p "CSV file name [redirects.csv]: " csvfile
    csvfile="${csvfile:-redirects.csv}"
    CSV=1
    echo "Writing results to $csvfile ..."
    exec >"$csvfile"
  fi
  exec 3<&-
fi

[[ ${#URLS[@]} -eq 0 ]] && { echo "No URLs provided." >&2; exit 1; }

csv_escape() { local s="${1//\"/\"\"}"; printf '"%s"' "$s"; }

# ---- Check a single URL ----
check_url() {
  local start="$1" current="$1" hops=0 result="" code="" next=""
  declare -A seen=()

[[ "$current" =~ ^https?:// ]] || current="http://$current"
  [[ $CSV -eq 0 ]] && printf '\n%s%s%s\n' "$BOLD" "$start" "$RESET"

while :; do
    local out
    out=$(curl -s -o /dev/null --max-time "$TIMEOUT" -A "$USER_AGENT" \
          -w '%{http_code} %{redirect_url}' "$current" 2>/dev/null)
    code="${out%% *}"
    next="${out#* }"; [[ "$next" == "$out" ]] && next=""

if [[ -z "$code" || "$code" == "000" ]]; then
      result="ERROR (connection failed/timeout)"
      [[ $CSV -eq 0 ]] && printf '  [%2d] %sERR%s  %s\n' "$hops" "$RED" "$RESET" "$current"
      break
    fi

local colour="$GREEN"
    [[ "$code" =~ ^3 ]] && colour="$YELLOW"
    [[ "$code" =~ ^[45] ]] && colour="$RED"
    [[ $CSV -eq 0 ]] && printf '  [%2d] %s%s%s  %s\n' "$hops" "$colour" "$code" "$RESET" "$current"

seen["$current"]=1

# Not a redirect (or redirect without Location) -> done
    if [[ ! "$code" =~ ^3 || -z "$next" ]]; then
      if [[ "$code" =~ ^2 ]]; then result="OK"
      elif [[ "$code" =~ ^3 ]]; then result="REDIRECT WITHOUT LOCATION"
      else result="HTTP $code"; fi
      break
    fi

if [[ -n "${seen[$next]:-}" ]]; then
      result="LOOP DETECTED"
      [[ $CSV -eq 0 ]] && printf '       %s↻ loops back to %s%s\n' "$RED" "$next" "$RESET"
      current="$next"; hops=$((hops + 1))
      break
    fi

hops=$((hops + 1))
    current="$next"

if (( hops > MAX_REDIRECTS )); then
      result="TOO MANY REDIRECTS (>$MAX_REDIRECTS)"
      break
    fi
  done

if [[ $CSV -eq 1 ]]; then
    printf '%s,%s,%s,%s,%s\n' "$(csv_escape "$start")" "$(csv_escape "$current")" \
      "$code" "$hops" "$(csv_escape "$result")"
  else
    local rc="$GREEN"; [[ "$result" != "OK" ]] && rc="$RED"
    printf '  %s→ %s%s | hops: %d | final: %s\n' "$rc" "$result" "$RESET" "$hops" "$current"
  fi

[[ "$result" == "OK" ]]
}

# ---- Main ----
[[ $CSV -eq 1 ]] && echo "url,final_url,final_status,hops,result"

total=0; failed=0
for raw in "${URLS[@]}"; do
  url="$(echo "$raw" | tr -d '\r' | xargs)"   # trim whitespace / CRLF
  [[ -z "$url" || "$url" == \#* ]] && continue
  total=$((total + 1))
  check_url "$url" || failed=$((failed + 1))
done

if [[ $CSV -eq 0 ]]; then
  printf '\n%sChecked %d URL(s): %d OK, %d with issues%s\n' "$CYAN" "$total" "$((total - failed))" "$failed" "$RESET"
fi

(( failed == 0 ))

1	#!/usr/bin/env bash
2	#
3	# check_redirects.sh - Follow and report HTTP redirect chains (max 10 hops).
4	#
5	# Run straight from a gist (it will ask for the URLs):
6	# bash <(curl -fsSL https://gist.veru.se/Veruse/87653b8402024210986ecec3c826e1b9/raw/HEAD/redirect-checker.sh)
7	# curl -fsSL https://gist.veru.se/Veruse/87653b8402024210986ecec3c826e1b9/raw/HEAD/redirect-checker.sh \| bash
8	#
9	# Arguments/flags work if you want to skip the prompts:
10	# bash <(curl -fsSL URL) https://a.com https://b.com
11	# bash <(curl -fsSL URL) -f urls.txt
12
13	set -uo pipefail
14
15	MAX_REDIRECTS=10
16	TIMEOUT=10
17	CSV=0
18	URL_FILE=""
19	USER_AGENT="Mozilla/5.0 (redirect-checker)"
20
21	if [[ -t 1 ]]; then
22	RED=$'\e[31m'; GREEN=$'\e[32m'; YELLOW=$'\e[33m'; CYAN=$'\e[36m'; BOLD=$'\e[1m'; RESET=$'\e[0m'
23	else
24	RED=""; GREEN=""; YELLOW=""; CYAN=""; BOLD=""; RESET=""
25	fi
26
27	usage() {
28	cat <<'EOF'
29	Usage: check_redirects.sh [options] [url ...]
30	(no URLs given = interactive prompts)
31
32	Options:
33	-f FILE Read URLs from FILE (one per line, # comments and blank lines ignored)
34	-m N Max redirects to follow (default: 10)
35	-t SECS Timeout per request in seconds (default: 10)
36	-c Output CSV (url,final_url,final_status,hops,result)
37	-h Show help
38	EOF
39	exit "${1:-0}"
40	}
41
42	while getopts ":f:m:t:ch" opt; do
43	case "$opt" in
44	f) URL_FILE="$OPTARG" ;;
45	m) MAX_REDIRECTS="$OPTARG" ;;
46	t) TIMEOUT="$OPTARG" ;;
47	c) CSV=1 ;;
48	h) usage 0 ;;
49	:) echo "Option -$OPTARG requires an argument." >&2; usage 1 ;;
50	\?) echo "Unknown option: -$OPTARG" >&2; usage 1 ;;
51	esac
52	done
53	shift $((OPTIND - 1))
54
55	command -v curl >/dev/null 2>&1 \|\| { echo "Error: curl is required." >&2; exit 1; }
56
57	# ---- Collect URLs ----
58	URLS=()
59	if [[ -n "$URL_FILE" ]]; then
60	[[ -r "$URL_FILE" ]] \|\| { echo "Error: cannot read $URL_FILE" >&2; exit 1; }
61	while IFS= read -r line \|\| [[ -n "$line" ]]; do URLS+=("$line"); done < "$URL_FILE"
62	fi
63	URLS+=("$@")
64
65	# ---- Interactive prompts (read from the terminal, so it works with curl \| bash) ----
66	TTY="${TTY_DEVICE:-/dev/tty}"
67	if [[ ${#URLS[@]} -eq 0 ]]; then
68	if ! { exec 3<"$TTY"; } 2>/dev/null; then
69	echo "Error: no URLs given and no terminal available to ask for them." >&2
70	usage 1
71	fi
72
73	echo "${BOLD}Redirect checker${RESET} (max $MAX_REDIRECTS redirects per URL)"
74	echo " 1) Check a single URL"
75	echo " 2) Paste a list of URLs"
76	echo " 3) Load URLs from a file"
77	read -r -u 3 -p "Choose [1-3]: " choice
78
79	case "$choice" in
80	1)
81	read -r -u 3 -p "URL: " line
82	URLS+=("$line")
83	;;
84	2)
85	echo "Paste URLs, one per line. Press Enter on an empty line when done:"
86	while IFS= read -r -u 3 line; do
87	line="${line//$'\r'/}"
88	[[ -z "${line// /}" ]] && break
89	URLS+=("$line")
90	done
91	;;
92	3)
93	read -r -u 3 -p "File path: " URL_FILE
94	URL_FILE="${URL_FILE/#\~/$HOME}"
95	[[ -r "$URL_FILE" ]] \|\| { echo "Error: cannot read $URL_FILE" >&2; exit 1; }
96	while IFS= read -r line \|\| [[ -n "$line" ]]; do URLS+=("$line"); done < "$URL_FILE"
97	;;
98	*)
99	echo "Invalid choice." >&2; exit 1 ;;
100	esac
101
102	read -r -u 3 -p "Save results as CSV instead of on-screen output? [y/N]: " ans
103	if [[ "$ans" =~ ^[Yy] ]]; then
104	read -r -u 3 -p "CSV file name [redirects.csv]: " csvfile
105	csvfile="${csvfile:-redirects.csv}"
106	CSV=1
107	echo "Writing results to $csvfile ..."
108	exec >"$csvfile"
109	fi
110	exec 3<&-
111	fi
112
113	[[ ${#URLS[@]} -eq 0 ]] && { echo "No URLs provided." >&2; exit 1; }
114
115	csv_escape() { local s="${1//\"/\"\"}"; printf '"%s"' "$s"; }
116
117	# ---- Check a single URL ----
118	check_url() {
119	local start="$1" current="$1" hops=0 result="" code="" next=""
120	declare -A seen=()
121
122	[[ "$current" =~ ^https?:// ]] \|\| current="http://$current"
123	[[ $CSV -eq 0 ]] && printf '\n%s%s%s\n' "$BOLD" "$start" "$RESET"
124
125	while :; do
126	local out
127	out=$(curl -s -o /dev/null --max-time "$TIMEOUT" -A "$USER_AGENT" \
128	-w '%{http_code} %{redirect_url}' "$current" 2>/dev/null)
129	code="${out%% *}"
130	next="${out#* }"; [[ "$next" == "$out" ]] && next=""
131
132	if [[ -z "$code" \|\| "$code" == "000" ]]; then
133	result="ERROR (connection failed/timeout)"
134	[[ $CSV -eq 0 ]] && printf ' [%2d] %sERR%s %s\n' "$hops" "$RED" "$RESET" "$current"
135	break
136	fi
137
138	local colour="$GREEN"
139	[[ "$code" =~ ^3 ]] && colour="$YELLOW"
140	[[ "$code" =~ ^[45] ]] && colour="$RED"
141	[[ $CSV -eq 0 ]] && printf ' [%2d] %s%s%s %s\n' "$hops" "$colour" "$code" "$RESET" "$current"
142
143	seen["$current"]=1
144
145	# Not a redirect (or redirect without Location) -> done
146	if [[ ! "$code" =~ ^3 \|\| -z "$next" ]]; then
147	if [[ "$code" =~ ^2 ]]; then result="OK"
148	elif [[ "$code" =~ ^3 ]]; then result="REDIRECT WITHOUT LOCATION"
149	else result="HTTP $code"; fi
150	break
151	fi
152
153	if [[ -n "${seen[$next]:-}" ]]; then
154	result="LOOP DETECTED"
155	[[ $CSV -eq 0 ]] && printf ' %s↻ loops back to %s%s\n' "$RED" "$next" "$RESET"
156	current="$next"; hops=$((hops + 1))
157	break
158	fi
159
160	hops=$((hops + 1))
161	current="$next"
162
163	if (( hops > MAX_REDIRECTS )); then
164	result="TOO MANY REDIRECTS (>$MAX_REDIRECTS)"
165	break
166	fi
167	done
168
169	if [[ $CSV -eq 1 ]]; then
170	printf '%s,%s,%s,%s,%s\n' "$(csv_escape "$start")" "$(csv_escape "$current")" \
171	"$code" "$hops" "$(csv_escape "$result")"
172	else
173	local rc="$GREEN"; [[ "$result" != "OK" ]] && rc="$RED"
174	printf ' %s→ %s%s \| hops: %d \| final: %s\n' "$rc" "$result" "$RESET" "$hops" "$current"
175	fi
176
177	[[ "$result" == "OK" ]]
178	}
179
180	# ---- Main ----
181	[[ $CSV -eq 1 ]] && echo "url,final_url,final_status,hops,result"
182
183	total=0; failed=0
184	for raw in "${URLS[@]}"; do
185	url="$(echo "$raw" \| tr -d '\r' \| xargs)" # trim whitespace / CRLF
186	[[ -z "$url" \|\| "$url" == \#* ]] && continue
187	total=$((total + 1))
188	check_url "$url" \|\| failed=$((failed + 1))
189	done
190
191	if [[ $CSV -eq 0 ]]; then
192	printf '\n%sChecked %d URL(s): %d OK, %d with issues%s\n' "$CYAN" "$total" "$((total - failed))" "$failed" "$RESET"
193	fi
194
195	(( failed == 0 ))