denilsonsa · xwang1498 · Jun 26, 2025 · Jul 18, 2025
diff --git a/README.md b/README.md
@@ -10,7 +10,7 @@ making the output prettier, more colorful, more compact, and easier to read.
 showing the ping responses in a *graphical* way at the terminal (by using
 colors and Unicode characters).
 
-`prettyping` is written in `bash` and `awk`, and is reported to work on many
+`prettyping` is written in `sh` and `awk`, and is reported to work on many
 different systems (Linux, Mac OS X, BSD…), as well as running on different
 versions of `awk` (`gawk`, `mawk`, `nawk`, `busybox awk`).
 
@@ -20,7 +20,7 @@ screenshots, videos at: <http://denilsonsa.github.io/prettyping/>
 Requirements
 ------------
 
-* `bash` (tested on 4.20, should work on versions as old as 2008)
+* posix-compatible shell, e.g. `bash` or `dash`
 * `awk` (either [gawk][], [mawk][], [nawk][] or [busybox awk][]; should work on
   `gawk` versions as old as 2008; should probably work on any other awk
   implementation)
@@ -35,7 +35,7 @@ Installation
 2. Make it executable: `chmod +x prettyping`
 
 That's all! No root permission is required. You can save and run it from any
-directory. As long as your user can run `ping`, `bash` and `awk`, then
+directory. As long as your user can run `ping`, `sh` and `awk`, then
 `prettyping` will work.
 
 Alternatively, you can download the latest tarball from GitHub: [![Latest release](https://img.shields.io/github/release/denilsonsa/prettyping.svg)](https://github.com/denilsonsa/prettyping/releases/latest)

diff --git a/mockping.sh b/mockping.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 #
 # This is just a mock ping program that reproduces the same output all the
 # time. It is used for testing/developing prettyping.
@@ -8,6 +8,7 @@ sample_output() {
 PING registro.br (200.160.2.3) 56(84) bytes of data.
 Request timeout for icmp_seq 1
 64 bytes from registro.br (200.160.2.3): icmp_seq=2 ttl=56 time=25.5 ms
+SIGWINCH
 64 bytes from registro.br (200.160.2.3): icmp_seq=3 ttl=56 time=55.7 ms
 64 bytes from registro.br (200.160.2.3): icmp_seq=4 ttl=56 time=75.2 ms
 ping: sendto: Network is down
@@ -49,7 +50,13 @@ rtt min/avg/max/mdev = 36.750/38.535/40.048/1.360 ms
 EOF
 }
 
-sample_output | while read line; do
-	echo -E "$line"
-	sleep 0.25s
+pgid=$(ps -o pgid= $$ | tr -d '[:space:]')
+
+sample_output | while read -r line; do
+	if [ "$line" = "SIGWINCH" ]; then
+		kill -WINCH -- -"$pgid"
+		continue
+	fi
+	printf '%s\n' "$line"
+	sleep "${SLEEP_SECS:-0.25}"
 done
diff --git a/prettyping b/prettyping
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 #
 # Written by Denilson Figueiredo de Sá <denilsonsa@gmail.com>
 # MIT license
@@ -78,172 +78,157 @@ All other parameters are passed directly to ping.
 EOF
 }
 
+MYNAME=$(basename "$0")
+
 # Thanks to people at #bash who pointed me at
 # https://web.archive.org/web/20100301171512/https://bash-hackers.org/wiki/doku.php/scripting/posparams
-parse_arguments() {
-	USE_COLOR=1
-	USE_MULTICOLOR=1
-	USE_UNICODE=1
-	USE_LEGEND=1
-	USE_GLOBALSTATS=1
-	USE_RECENTSTATS=1
-
-	if [ -t 1 ]; then
-		IS_TERMINAL=1
-	else
-		IS_TERMINAL=0
-	fi
-
-	LAST_N=60
-	OVERRIDE_COLUMNS=0
-	OVERRIDE_LINES=0
-	RTT_MIN=auto
-	RTT_MAX=auto
-
-	PING_BIN="ping"
-	#PING_BIN="./mockping.awk"
-	PING_PARAMS=( )
-
-	AWK_BIN="awk"
-	AWK_PARAMS=( )
-
-	while [[ $# != 0 ]] ; do
-		case "$1" in
-			-h | -help | --help )
-				print_help
-				exit
-				;;
-
-			# Forbidden ping parameters within prettyping:
-			-f )
-				echo "${MYNAME}: You can't use the -f (flood) option."
-				exit 1
-				;;
-			-R )
-				# -R prints extra information at each ping response.
-				echo "${MYNAME}: You can't use the -R (record route) option."
-				exit 1
-				;;
-			-q )
-				echo "${MYNAME}: You can't use the -q (quiet) option."
-				exit 1
-				;;
-			-v )
-				# -v enables verbose output. However, it seems the output with
-				# or without this option is the same. Anyway, prettyping will
-				# strip this parameter.
-				;;
-			# Note:
-			#  Small values for -s parameter prevents ping from being able to
-			#  calculate RTT.
-
-			# New parameters:
-			-a )
-				# TODO: Implement audible ping for responses or for missing packets
-				;;
-
-			-color         | --color         ) USE_COLOR=1 ;;
-			-nocolor       | --nocolor       ) USE_COLOR=0 ;;
-			-multicolor    | --multicolor    ) USE_MULTICOLOR=1 ;;
-			-nomulticolor  | --nomulticolor  ) USE_MULTICOLOR=0 ;;
-			-unicode       | --unicode       ) USE_UNICODE=1 ;;
-			-nounicode     | --nounicode     ) USE_UNICODE=0 ;;
-			-legend        | --legend        ) USE_LEGEND=1 ;;
-			-nolegend      | --nolegend      ) USE_LEGEND=0 ;;
-			-globalstats   | --globalstats   ) USE_GLOBALSTATS=1 ;;
-			-noglobalstats | --noglobalstats ) USE_GLOBALSTATS=0 ;;
-			-recentstats   | --recentstats   ) USE_RECENTSTATS=1 ;;
-			-norecentstats | --norecentstats ) USE_RECENTSTATS=0 ;;
-			-terminal      | --terminal      ) IS_TERMINAL=1 ;;
-			-noterminal    | --noterminal    ) IS_TERMINAL=0 ;;
-
-			-awkbin  | --awkbin  ) AWK_BIN="$2"  ; shift ;;
-			-pingbin | --pingbin ) PING_BIN="$2" ; shift ;;
-
-			#TODO: Check if these parameters are numbers.
-			-last    | --last    ) LAST_N="$2"           ; shift ;;
-			-columns | --columns ) OVERRIDE_COLUMNS="$2" ; shift ;;
-			-lines   | --lines   ) OVERRIDE_LINES="$2"   ; shift ;;
-			-rttmin  | --rttmin  ) RTT_MIN="$2"          ; shift ;;
-			-rttmax  | --rttmax  ) RTT_MAX="$2"          ; shift ;;
-
-			* )
-				PING_PARAMS+=("$1")
-				;;
-		esac
+USE_COLOR=1
+USE_MULTICOLOR=1
+USE_UNICODE=1
+USE_LEGEND=1
+USE_GLOBALSTATS=1
+USE_RECENTSTATS=1
+
+if [ -t 1 ]; then
+	IS_TERMINAL=1
+else
+	IS_TERMINAL=0
+fi
+
+LAST_N=60
+OVERRIDE_COLUMNS=0
+OVERRIDE_LINES=0
+RTT_MIN=0
+RTT_MAX=0
+
+PING_BIN="ping"
+#PING_BIN="./mockping.sh"
+
+AWK_BIN="awk"
+
+skipnext=0
+for arg; do
+	if [ "$skipnext" -eq 1 ]; then
+		skipnext=0
 		shift
-	done
-
-	if [[ "${RTT_MIN}" -gt 0 && "${RTT_MAX}" -gt 0 && "${RTT_MIN}" -ge "${RTT_MAX}" ]] ; then
-		echo "${MYNAME}: Invalid --rttmin and -rttmax values."
-		exit 1
+		continue
 	fi
+	case "$1" in
+		-h | -help | --help )
+			print_help
+			exit
+			;;
+
+		# Forbidden ping parameters within prettyping:
+		-f )
+			echo "${MYNAME}: You can't use the -f (flood) option."
+			exit 1
+			;;
+		-R )
+			# -R prints extra information at each ping response.
+			echo "${MYNAME}: You can't use the -R (record route) option."
+			exit 1
+			;;
+		-q )
+			echo "${MYNAME}: You can't use the -q (quiet) option."
+			exit 1
+			;;
+		-v )
+			# -v enables verbose output. However, it seems the output with
+			# or without this option is the same. Anyway, prettyping will
+			# strip this parameter.
+			;;
+		# Note:
+		#  Small values for -s parameter prevents ping from being able to
+		#  calculate RTT.
+
+		# New parameters:
+		-a )
+			# TODO: Implement audible ping for responses or for missing packets
+			;;
+
+		-color         | --color         ) USE_COLOR=1 ;;
+		-nocolor       | --nocolor       ) USE_COLOR=0 ;;
+		-multicolor    | --multicolor    ) USE_MULTICOLOR=1 ;;
+		-nomulticolor  | --nomulticolor  ) USE_MULTICOLOR=0 ;;
+		-unicode       | --unicode       ) USE_UNICODE=1 ;;
+		-nounicode     | --nounicode     ) USE_UNICODE=0 ;;
+		-legend        | --legend        ) USE_LEGEND=1 ;;
+		-nolegend      | --nolegend      ) USE_LEGEND=0 ;;
+		-globalstats   | --globalstats   ) USE_GLOBALSTATS=1 ;;
+		-noglobalstats | --noglobalstats ) USE_GLOBALSTATS=0 ;;
+		-recentstats   | --recentstats   ) USE_RECENTSTATS=1 ;;
+		-norecentstats | --norecentstats ) USE_RECENTSTATS=0 ;;
+		-terminal      | --terminal      ) IS_TERMINAL=1 ;;
+		-noterminal    | --noterminal    ) IS_TERMINAL=0 ;;
+
+		-awkbin  | --awkbin  ) AWK_BIN="$2"  ; skipnext=1 ;;
+		-pingbin | --pingbin ) PING_BIN="$2" ; skipnext=1 ;;
+
+		#TODO: Check if these parameters are numbers.
+		-last    | --last    ) LAST_N="$2"           ; skipnext=1 ;;
+		-columns | --columns ) OVERRIDE_COLUMNS="$2" ; skipnext=1 ;;
+		-lines   | --lines   ) OVERRIDE_LINES="$2"   ; skipnext=1 ;;
+		-rttmin  | --rttmin  ) RTT_MIN="$2"          ; skipnext=1 ;;
+		-rttmax  | --rttmax  ) RTT_MAX="$2"          ; skipnext=1 ;;
+
+		* )
+			# unprocessed parameters will cycle to the front of $@ to be passed to `ping`
+			set -- "$@" "$1"
+			;;
+	esac
+	shift
+done
+
+if [ "${RTT_MIN}" -gt 0 ] && [ "${RTT_MAX}" -gt 0 ] && [ "${RTT_MIN}" -ge "${RTT_MAX}" ] ; then
+	echo "${MYNAME}: Invalid --rttmin and -rttmax values."
+	exit 1
+fi
+
+if [ $# -eq 0 ] ; then
+	echo "${MYNAME}: Missing parameters, use --help for instructions."
+	exit 1
+fi
+
+# Workaround for mawk:
+# https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=593504
+awk_version="$(echo | "${AWK_BIN}" -W version 2>&1)"
+case "$awk_version" in
+	mawk*) AWK_PARAMS="-W interactive" ;;
+esac
 
-	if [[ "${#PING_PARAMS[@]}" = 0 ]] ; then
-		echo "${MYNAME}: Missing parameters, use --help for instructions."
-		exit 1
-	fi
 
-	# Workaround for mawk:
-	# https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=593504
-	local version="$(echo | "${AWK_BIN}" -W version 2>&1)"
-	if [[ "${version}" == mawk* ]] ; then
-		AWK_PARAMS+=(-W interactive)
-	fi
-}
-
-MYNAME=`basename "$0"`
-parse_arguments "$@"
 
 
 export LC_ALL=C
 
-# Warning! Ugly code ahead!
-# The code is so ugly that the comments explaining it are
-# bigger than the code itself!
-#
-# Suppose this:
-#
-#   cmd_a | cmd_b &
-#
-# I need the PID of cmd_a. How can I get it?
-# In bash, $! will give me the PID of cmd_b.
-#
-# So, I came up with this ugly solution: open a subshell, like this:
-#
-# (
-# 	cmd_a &
-# 	echo "This is the PID I want $!"
-# 	wait
-# ) | cmd_b
-
+# Ignore SIGINT (Ctrl-C) downstream of ping, so the pipeline can cleanly finish when ping is interrupted.
 
-# Ignore Ctrl+C here.
-# If I don't do this, this shell script is killed before
-# ping and gawk can finish their work.
-trap '' 2
+"${PING_BIN}" "$@" 2>&1 | (
+	trap '' INT
 
-# Now the ugly code.
-(
-	"${PING_BIN}" "${PING_PARAMS[@]}" &
-	PING_PID="$!"
-
-	# Commented out, because it looks like this line is not needed
-	#trap "kill -2 $PING_PID ; exit 1" 2  # Catch Ctrl+C here
-
-	wait
-) 2>&1 | (
 	if [ "${IS_TERMINAL}" = 1 ]; then
 		# Print a message to notify the awk script about terminal size change.
-		trap "echo SIGWINCH" 28
+		trap 'sigwinch=1; echo SIGWINCH' WINCH
 	fi
 
-	# The trap must be in another subshell because otherwise it will interrupt
-	# the "wait" commmand.
-	while read line; do
-		echo -E "$line"
+	sigwinch=0
+	while true; do
+		if ! read -r line; then
+			# some shells will interrupt read for the SIGWINCH, in which case we need to restart it
+			if [ "$sigwinch" -eq 1 ]; then
+				sigwinch=0
+				continue
+			else
+				break
+			fi
+		fi
+		printf '%s\n' "$line"
 	done
-) 2>&1 | "${AWK_BIN}" "${AWK_PARAMS[@]}" '
+) 2>&1 | (
+	trap '' INT
+
+	"${AWK_BIN}" ${AWK_PARAMS:+$AWK_PARAMS} '
 # Weird that awk does not come with abs(), so I need to implement it.
 function abs(x) {
 	return ( (x < 0) ? -x : x )
@@ -478,12 +463,12 @@ function print_received_response(rtt, block_index) {
 	} else {
 		block_index = 1 + int((rtt - BLOCK_RTT_MIN) * (BLOCK_LEN - 2) / BLOCK_RTT_RANGE)
 	}
-	printf( BLOCK[block_index] )
+	printf( BLOCK[block_index] ESC_DEFAULT )
 	CURR_COL++
 }
 
 function print_missing_response(rtt) {
-	printf( ESC_RED "!" )
+	printf( ESC_RED "!" ESC_DEFAULT )
 	CURR_COL++
 }
 
@@ -889,3 +874,4 @@ BEGIN {
 	# Not needed when the output is a terminal, but does not hurt either.
 	fflush()
 }'
+)