Determine if only one instance is running: Difference between revisions
Determine if only one instance is running (view source)
Revision as of 09:43, 17 November 2019
, 4 years ago→{{header|Nim}}
m (Remove needless import) |
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Line 790:
=={{header|Nim}}==
fcntl based:
<lang nim>import os, posix
Line 809 ⟶ 810:
sleep 1000
echo "Fin!"</lang>
Unix Domain Socket based:
<lang nim>import options, os, std/monotimes
from net import newSocket, bindUnix
from nativesockets import AF_UNIX, SOCK_DGRAM, IPPROTO_IP
from posix import EADDRINUSE
const sockAddr = "\0com.myapp.sock" # Linux will delete this when the application ends
# notice the prefixed null byte, it's the Linux abstract namespace
proc server()=
echo "Unique instance detected"
proc client()=
echo "Duplicate instance detected"
when isMainModule:
var
sock = newSocket(AF_UNIX, SOCK_DGRAM, IPPROTO_IP)
isUnique: Option[bool]
try:
sock.bindUnix(sock_addr)
is_unique = some true
except OSError:
if cint(osLastError()) == EADDRINUSE:
isUnique = some false
else:
raise getCurrentException()
if unlikely is_unique.isNone:
echo "Error detecting uniqueness" # unreachable
else:
if isUnique.unsafeGet():
server()
else:
client()</lang>
=={{header|OCaml}}==
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