On 2018-06-26 04:33, john doe wrote:
> In gnupg2 the use of dirmngr utility is required to interact with a keyserver.
> Dirmngr requires that '/etc/resolv.conf' be populated with my name servers.
> That means that everytime the dns changes (new network ...) I need to manually
> edit that file.
> How can I let Cygwin update that file whenever the DNS is changed?
Attached an awk script to generate resolv.conf from Windows ipconfig /all
output, run from .cygwin_profile (sourced under Cygwin from login .bash_profile)
using the stanza below: it only replaces an existing writable /etc/resolv.conf
when the content changes - touch, chown, chmod /etc/resolv.conf to enable.
# update /etc/resolv.conf if changed
c=/etc/resolv.conf
test -w $c && \
i=$(/usr/bin/which -- ipconfig) && \
r=$(/usr/bin/which -- resolv.awk) && \
t=$(/bin/mktemp -t -- resolv.conf.$$.XXXXXXXX) && \
if $i /all | $r > $t; then
/usr/bin/cmp -s -- $t $c || \
/bin/cp -fv -- $t $c
/bin/rm -f -- $t
fi
unset c i r t
This could be used in a bash script run from a Windows scheduled task when a
relevant DHCP event occurs: you can find DHCP events by checking Windows Admin
Tools/Event Viewer/Window Logs/System/Filter Current Log/Event
Sources/Dhcp-Client,DHCPv6-Client, or a similar PowerShell script.
--
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
#!/usr/bin/awk -f
# resolv.awk - create Windows resolv.conf from ipconfig /all output
{ sub( /\r/, "", $NF) } # trim \r
# collect DNS domain suffixes
/D[Nn][Ss]\sSuffix[^:]*:\s\S/ { domain[$NF] = $NF }
# collect DNS search suffixes
/Search\sList[^:]*:\s\S/ { search[$NF] = $NF }
# collect DNS server IP addresses
/DNS\sServers[^:]*:\s\S/ { dns = 1 } # enable
dns && $NF ~ /^[0-9.]+$/ { nameserver[++ns] = $NF } # collect
dns && $NF !~ /^[0-9.]+$/ { dns = 0 } # disable
# output unique resolv.conf entries
END {
for (n = 1; n <= ns; ++n) { print "nameserver", nameserver[n] }
for (d in domain) { print "domain", domain[d] }
p = "search"
for (s in search) {
printf "%s %s", p, search[s]
p = ""
}
if (!p) { print p }
}
--
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