On 01Mar2017 13:55, rob...@forzasilicon.com <rob...@forzasilicon.com> wrote:
I'm relatively new to Python, and I am having some trouble with one of my
scripts. Basically, this script connects to a server via ssh, runs Dell's
omreport output, and then externally pipes it to a mail script in cron. The
script uses an external call to grep via subprocess, but I would like to
internalize everything to run in Python. I've read that re can accomplish the
filtering, but I am having trouble getting it to duplicate what I already
have.
##### USING EXTERNAL GREP #####
# display RAID controller info
cmd = ['ssh r...@server.ip -C \"/opt/dell/srvadmin/sbin/omreport storage
vdisk\"']
print '########## Array Status ##########'
p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
Might I recommend that you drop the shell quotes and invoke ssh directly?
cmdargs = [ 'ssh', 'r...@server.ip', '-C',
'/opt/dell/srvadmin/sbin/omreport storage vdisk' ]
p = subprocess.Popen(cmdargs, shell=False, stdout=subprocess.PIPE)
And since shell=False is the default you can leave it off. It is just generally
better to avoid using the shell for commands as it introduces a layer of
quoting and escaping, usually pointlessly and always with a risk of misuse.
if call(["grep", "-i", "ID"], stdin=p.stdout) != 0:
You're just looking for "id" in any case. That's fairly loose. More commentry
below the output...
[...]
This gives me:
ID : 0
Layout : RAID-1
Associated Fluid Cache State : Not Applicable
----
vs the full output of:
########## Array Status ##########
List of Virtual Disks in the System
Controller PERC H310 Mini (Embedded)
ID : 0
Status : Ok
Name : Main
State : Ready
Hot Spare Policy violated : Not Assigned
Encrypted : Not Applicable
Layout : RAID-1
Size : 2,794.00 GB (3000034656256 bytes)
T10 Protection Information Status : No
Associated Fluid Cache State : Not Applicable
Device Name : /dev/sda
Bus Protocol : SATA
Media : HDD
Read Policy : No Read Ahead
Write Policy : Write Through
Cache Policy : Not Applicable
Stripe Element Size : 64 KB
Disk Cache Policy : Enabled
##### END ####
I've been tinkering around with re, and the only code that I've come up with
that doesn't give me a type error is this:
[...]
for line in p.stdout:
final = re.findall('ID', line, re.DOTALL)
print final
[...]
[]
[]
[]
['ID']
[...]
Findall returns a list of all the matches. What you want is "if findall found
anything, print the whole line", and for that you would only need find() (since
it is enough to find just one match, not all of them).
Might I suggest you don't use re at all? It has its uses but for your initial
needs it is not necessary, and regexps are easy to get wrong (not to mention
slow). Do a fixed string split:
# trim the trailing newline and other padding if any
line = line.strip()
try:
lhs, rhs = split(line, ':', 1)
except ValueError:
# no colon, probably a heading
... handle a heading, if you care ...
else:
field = lhs.strip()
value = rhs.strip()
if field == 'ID':
... note the controller id ...
elif field == 'Layout':
... note the layout value ...
... whatever other fields you care about ...
You can see that in this way you can handle fields very specificly as you see
fit. Some RAID monitoring tools produce quite long reports, so you can also
track state (what heading/controller/raidset am I in at present?) and build a
data structure for better reporting.
As an example, have a gander at this:
https://pypi.python.org/pypi/cs.app.megacli/20160310
which I wrote for IBM MegaRAIDs; it also does Dell PowerEdge (PERC)
controllers.
It is deliberately Python 2 BTW, because it had to run on RHEL 5 which had
Python 2.4 as the vendor supplied python.
Cheers,
Cameron Simpson <c...@zip.com.au>
Some people, when confronted with a problem, think "I know, I'll use regular
expressions. Now they have two problems."
- Jamie Zawinski, in alt.religion.emacs
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