When I was updating the Network Migration with BGP Local-AS Feature blog post, I wanted to execute the same command (show ip bgp) on all routers in my network.

Not a problem: since Dan Partelly added the netlab exec command, it’s as simple as netlab exec * show ip bgp. Well, not exactly; there are still a few quirks.

The easy one first: any decent Unix shell thinks it should expand the * in the command line, resulting in a command that includes every filename in the current directory. Not exactly helpful; we have to quote the * to make the command work:

$ netlab exec '*' show ip bgp

Here are the first few lines produced by the above command:

Connecting to clab-LocalAS_Migr-custa using SSH port 22, executing show ip bgp



BGP table version is 4, local router ID is 10.0.0.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
              t secondary path, L long-lived-stale,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *>   10.6.6.0/24      10.1.0.10                              0 64510 64500 i
 *>   10.8.8.0/24      0.0.0.0                  0         32768 i
 *>   10.9.9.0/24      10.1.0.10                              0 64510 65100 iConnection to clab-localas_migr-custa closed by remote host.

We have the results we need, but they’re full of noise. For example, we should get rid of the BGP table legend. We can use the | begin Network filter on Cisco IOS to do that, but it’s a bit hard to add that filter to a bash command without starting a Linux pipe. Fortunately, we can quote the | symbol:

$ netlab exec '*' show ip bgp \| begin Network
Connecting to clab-LocalAS_Migr-custa using SSH port 22, executing show ip bgp | begin Network


     Network          Next Hop            Metric LocPrf Weight Path
 *>   10.6.6.0/24      10.1.0.10                              0 64510 64500 i
 *>   10.8.8.0/24      0.0.0.0                  0         32768 i
 *>   10.9.9.0/24      10.1.0.10                              0 64510 65100 iConnection to clab-localas_migr-custa closed by remote host.

It would also be nice to get rid of the Connecting to… header but still retain some information about the device on which we’re executing the command. Let’s use the -q (quiet) flag together with the --header flag:

$ netlab exec -q --header '*' show ip bgp \| begin Network
================================================================================
custa: executing show ip bgp | begin Network
================================================================================


     Network          Next Hop            Metric LocPrf Weight Path
 *>   10.6.6.0/24      10.1.0.10                              0 64510 64500 i
 *>   10.8.8.0/24      0.0.0.0                  0         32768 i
 *>   10.9.9.0/24      10.1.0.10                              0 64510 65100 iConnection to clab-localas_migr-custa closed by remote host.

Finally, there’s the annoying “Connection closed by remote host” message appended at the end of the last line. I couldn’t get rid of it (and StackOverflow and friends were no help) or persuade Cisco IOS to terminate the last line with a newline; if you have an idea, please add a comment.