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modified post d0b0a by Anonymous on Sun 26th Feb 2023 17:57
original post 681dac5 by Anonymous on Sun 26th Feb 2023 17:31
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#!/usr/bin/ksh93

1	1		#!/usr/bin/ksh93
2	2
3	3		#
4	4		# find_free_tcp_port1.ksh - find a free tcp port
5	5		#
6	6		# Written by Roland Mainz <roland.mainz@nrubsig.org>
7	7		#
8	8
9	9		#
10	10		# simple netstat -n parser
11	11		#
12	12		function netstat_list_connections
13	13		{
	14	+	# fixme: should be set -o nounset clean
14	15		nameref data=$1
15	16
16	17		typeset -a data.connections
17	18
18	19		typeset nsout="$(LC_ALL='POSIX' netstat -n)"
19	20
20	21		while read i ; do
21	22		leftover="${i/~(Elrx)
22	23		(?: # non-capturing group
23	24		#
24	25		# regex group for tcpudp
25	26		#
26	27		(tcp\|tcp6\|udp) # Proto
27	28		[[:space:]]+
28	29		([[:digit:]]+) # Recv-Q
29	30		[[:space:]]+
30	31		([[:digit:]]+) # Send-Q
31	32		[[:space:]]+
32	33		([^[:space:]]+) # Local Address
33	34		[[:space:]]+
34	35		([^[:space:]]+) # Foreign Address
35	36		[[:space:]]+
36	37		([^[:space:]]+) # State
37	38		\|
38	39		#
39	40		# regex for unix
40	41		#
41	42		(unix) # Proto
42	43		[[:space:]]+
43	44		([[:digit:]]+) # RefCnt
44	45		[[:space:]]+
45	46		(\[.+\]) # Flags
46	47		[[:space:]]+
47	48		([^[:space:]]+) # Type
48	49		[[:space:]]+
49	50		([^[:space:]]*?) # State
50	51		[[:space:]]+
51	52		([[:digit:]]+) # I-Node
52	53		(?:
	54	+	# Path is optional
53	55		\|
54	56		[[:space:]]+
55	57		([^[:space:]]+) # Path
56	58		)
57	59		)
58	60		/X}"
59	61
60		-	# if the regex above did not match then .sh.match remains
	62	+	# if the regex above did not match then .sh.match
61		-	# untouched.
	63	+	# remains untouched, so we might see data from the
62		-	# so we check the leftover whether it just contains the
	64	+	# previous round.
63		-	# dummy value of "X" to indicate a successful regex match
	65	+	# so we check the "leftover" var whether it just
	66	+	# contains the dummy value of "X" to indicate a
64	68		if [[ "$leftover" == 'X' ]] ; then
65	69		#print -v .sh.match
66	70
67	71		if [[ "${.sh.match[1]}" != '' ]] ; then
68	72		data.connections+=(
69	73		typeset proto="${.sh.match[1]}"
70	74		typeset recv_q="${.sh.match[2]}"
71	75		typeset send_q="${.sh.match[3]}"
72	76		typeset local_address="${.sh.match[4]}"
73	77		typeset foreign_address="${.sh.match[5]}"
74	78		typeset state="${.sh.match[6]}"
75	79		)
76	80		elif [[ "${.sh.match[7]}" != '' ]] ; then
77	81		data.connections+=(
78	82		typeset proto="${.sh.match[7]}"
79	83		typeset refcnt="${.sh.match[8]}"
80	84		typeset flags="${.sh.match[9]}"
81	85		typeset type="${.sh.match[10]}"
82	86		typeset state="${.sh.match[11]}"
83	87		typeset inode="${.sh.match[12]}"
84	88		typeset path="${.sh.match[13]}"
85	89		)
86	90		fi
87	91		else
88	92		:
89		-	#printf "leftover=%q\n" "${leftover}"
	93	+	printf "leftover=%q\n" "${leftover}"
90	94		fi
91	95		done <<<"$nsout"
92	96
93	97		return 0
94	98		}
95	99
96	100		function main
97	101		{
98	102		compound c
99	103		netstat_list_connections c
100		-	# print -v c
	104	+	print -v c
101	105		#set -x
102	106		for i in "${!c.connections[@]}" ; do
103	107		nameref n=c.connections[$i]
104	108		if [[ "${n.proto}" == ~(El)tcp && "${n.local_address}" == ~(Elr)(127\.0\..+\|::1):[[:digit:]]+ ]] ; then
105	109		#print -v n
106	110		printf $"port = %q\n" "${n.local_address##*:}"
107	111		fi
108	112		done
109	113
110	114		}
111	115
112	116		main
113	117		# EOF.
114	118