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Groups > comp.os.linux.networking > #1218 > unrolled thread
| Started by | <fab@slick.airforce-one.org> |
|---|---|
| First post | 2012-03-30 17:44 +0000 |
| Last post | 2012-04-05 19:07 +0100 |
| Articles | 6 — 6 participants |
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How to know if eth0 is up? <fab@slick.airforce-one.org> - 2012-03-30 17:44 +0000
Re: How to know if eth0 is up? Chris Davies <chris-usenet@roaima.co.uk> - 2012-03-30 19:33 +0100
Re: How to know if eth0 is up? Bit Twister <BitTwister@mouse-potato.com> - 2012-03-30 19:57 +0000
Re: How to know if eth0 is up? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-03-31 21:22 +0000
Re: How to know if eth0 is up? J G Miller <miller@yoyo.ORG> - 2012-03-30 21:12 +0000
Re: How to know if eth0 is up? Mark Evans <mpe@anacon.freeserve.co.uk> - 2012-04-05 19:07 +0100
| From | <fab@slick.airforce-one.org> |
|---|---|
| Date | 2012-03-30 17:44 +0000 |
| Subject | How to know if eth0 is up? |
| Message-ID | <4f75f0eb$0$19106$426a34cc@news.free.fr> |
Hello. I'd like to know if there is a command line instruction or a /proc/ entry that tells reliably if a cable is hooked in an ethernet port (typically, to know at boot if I must use my dhcp client on eth0, or look for a WIFI cell). I have found /proc/net/dev but it shows eth0 even though no cable is plugged in. Thanks. -- F. Delente
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| From | Chris Davies <chris-usenet@roaima.co.uk> |
|---|---|
| Date | 2012-03-30 19:33 +0100 |
| Message-ID | <6sah49xkda.ln2@news.roaima.co.uk> |
| In reply to | #1218 |
fab@slick.airforce-one.org wrote: > I'd like to know if there is a command line instruction or a /proc/ > entry that tells reliably if a cable is hooked in an ethernet port Either mii-tool or ethtool. Chris
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| From | Bit Twister <BitTwister@mouse-potato.com> |
|---|---|
| Date | 2012-03-30 19:57 +0000 |
| Message-ID | <slrnjnc41d.6pk.BitTwister@wb.home.test> |
| In reply to | #1218 |
On 30 Mar 2012 17:44:11 GMT, <fab@slick.airforce-one.org> wrote: > Hello. Hi. You know if you were to read http://www.catb.org/~esr/faqs/smart-questions.html it suggest giving meaningful information pertinent to your setup. At a minimum I would suggest which linux distribution, release, and Ethernet card. That kind of information might get you some exact answers. NIC may dictate which tool (ethtool, or mii-tool). Distribution might get you what net function can be used to make you code much more maintainable as time goes by. > I'd like to know if there is a command line instruction or a /proc/ > entry that tells reliably if a cable is hooked in an ethernet port > (typically, to know at boot if I must use my dhcp client on eth0, or > look for a WIFI cell). > > I have found /proc/net/dev but it shows eth0 even though no cable is > plugged in. On my distribution, carrier status is found over in /sys/class/net and the network-functions script has a check_link_down function to do all the dirty work. Based on the lack of any detailed information, I can only suggest trying something like parsing the output from something like LC_ALL=C ip link show dev eth0
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| From | Jorgen Grahn <grahn+nntp@snipabacken.se> |
|---|---|
| Date | 2012-03-31 21:22 +0000 |
| Message-ID | <slrnjnetc5.1ls.grahn+nntp@frailea.sa.invalid> |
| In reply to | #1220 |
On Fri, 2012-03-30, Bit Twister wrote: > On 30 Mar 2012 17:44:11 GMT, <fab@slick.airforce-one.org> wrote: >> Hello. > > Hi. You know if you were to read > http://www.catb.org/~esr/faqs/smart-questions.html > it suggest giving meaningful information pertinent to your setup. > > At a minimum I would suggest which linux distribution, release, and > Ethernet card. That kind of information might get you some exact answers. ... A general answer is more enlightening for the rest of us, though. ... >> I have found /proc/net/dev but it shows eth0 even though no cable is >> plugged in. > > On my distribution, carrier status is found over in /sys/class/net and ... ... like this one. I know kernel interfaces change now and then, but I'd like to see one modern distribution which didn't enable that one. (Thanks, by the way!) /Jorgen -- // Jorgen Grahn <grahn@ Oo o. . . \X/ snipabacken.se> O o .
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| From | J G Miller <miller@yoyo.ORG> |
|---|---|
| Date | 2012-03-30 21:12 +0000 |
| Message-ID | <jl57jn$7md$3@dont-email.me> |
| In reply to | #1218 |
On Friday, March 30th, 2012, at 17:44:11 +0000, FAB wrote:
> I'd like to know if there is a command line instruction or a /proc/
> entry that tells reliably if a cable is hooked in an ethernet port
> (typically, to know at boot if I must use my dhcp client on eth0, or
> look for a WIFI cell).
Which is quite a different thing to your "subject" which could be
answered perhaps with
ifconfig eth0 | egrep 'UP' | egrep 'RUNNING'
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
As others have suggested perhaps
ethtool eth0 | egrep "Link detected"
Link detected: yes
--
The Paul Ryan Budget -- Robs from the poor and gives to the rich.
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| From | Mark Evans <mpe@anacon.freeserve.co.uk> |
|---|---|
| Date | 2012-04-05 19:07 +0100 |
| Message-ID | <jj3159-brb.ln1@server.anacon.no-ip.org> |
| In reply to | #1218 |
fab@slick.airforce-one.org wrote: > > I'd like to know if there is a command line instruction or a /proc/ > entry that tells reliably if a cable is hooked in an ethernet port > (typically, to know at boot if I must use my dhcp client on eth0, or > look for a WIFI cell). Have you looked at ifplugd?
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