cat / sed process weird characters


 
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# 1  
Old 08-03-2011
cat / sed process weird characters

Hi everyone,
I'm trying to write a shell script that process a log file. The log format is generally:
(8 digit hex of unix time),(system ID),(state)\n
My shell script gets the file from the web, saves it in a local text directory. I then want to change the hex to decimal, convert from unix time to a day/month/year MST format and write out.

I have something that *mostly* works, by downloading the file, opening it with cat, piping the result to sed, using sed to get all the hex values and looping through them.

Unfortunately, there's a bug in the software that produces the log and for some systems the id isn't defined (someone probably forgot to initialize that variable), and it produces a line that looks like: 3B6A7227,√剃,0

When I open this file with cat, the output for lines like that usually just contains a lot of question marks. This is the line I'm using to isolate the hex values:

Code:
cat ~/Downloads/log.txt | sed 's/[^0-9A-Za-z,\n]//g' | sed 's/,.*,[0,1]$//'

Originally I just had the second "sed"; I added the first one in an attempt to remove all the "weird" characters. Unfortunately, when I run this, it comes out as a list of hex numbers EXCEPT for the weird entries. These entries now have their hex number, a comma, then a number of question marks (and sometimes a decimal number), then another comma and the state.

How can I get rid of these? I realize the bug in the logging code needs to be fixed, but I don't have control over that, i'm just trying to clean up the log file.

Thanks!
# 2  
Old 08-03-2011
I find "cat -vt" pretty nice for making the invisible and odd more behaved. If they slip you a ^J or comma you are a goner, though:
Code:
$ all256|cat -vt
^@^A^B^C^D^E^F^G^H^I
^K^L^M^N^O^P^Q^R^S^T^U^V^W^X^Y^Z^[^\^]^^^_ !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~^?M-^@M-^AM-^BM-^CM-^DM-^EM-^FM-^GM-^HM-^IM-
M-^KM-^LM-^MM-^NM-^OM-^PM-^QM-^RM-^SM-^TM-^UM-^VM-^WM-^XM-^YM-^ZM-^[M-^\M-^]M-^^M-^_M- M-!M-"M-#M-$M-%M-&M-'M-(M-)M-*M-+M-,M--M-.M-/M-0M-1M-2M-3M-4M-5M-6M-7M-8M-9M-:M-;M-<M-=M->M-?M-@M-AM-BM-CM-DM-EM-FM-GM-HM-IM-JM-KM-LM-MM-NM-OM-PM-QM-RM-SM-TM-UM-VM-WM-XM-YM-ZM-[M-\M-]M-^M-_M-`M-aM-bM-cM-dM-eM-fM-gM-hM-iM-jM-kM-lM-mM-nM-oM-pM-qM-rM-sM-tM-uM-vM-wM-xM-yM-zM-{M-|M-}M-~M-^?

If you write a C or PERL app, you can ignore ^j without 2 commas and reverse ignore comma if more than 2, pushing the user id back to a fixed value. Maybe sometimes they cannot determine the user name from id #, and write the binary id # ?
# 3  
Old 08-03-2011
Untested idea to clean the file by removing any characters except 0-9 A-Z a-z commas and newlines using the unix "tr" command.

Code:
cat ~/Downloads/log.txt | while read old_line
do
         echo "${old_line}"| tr -dc '[0-9][A-Z][a-z],\n'
done

If this does not solve your problem, please post sample data which shows a couple of good lines and a couple of bad lines when displayed by the unix "od" command (which will show exactly what characters are in the file). We don't need the whole file.
Code:
cat ~/Downloads/log.txt | od -xc

This User Gave Thanks to methyl For This Post:
# 4  
Old 08-03-2011
Methyl - your idea would work, but when I try it, I get an error: 'tr: illegal byte sequence'

Here is a sample data set:
(in plaintext):

Code:
3B698960,eSWPump,0
3B698C36,sHeatPre,1
3B698C36,ePHPump,1
3B698C36,eSWPump,1
3B698CB4,!˛ˇ√8,1
3B698CB4,eHWRPump,1
3B698CB4,››√‰ƒ,1
3B698CB4,eDownHRV,1
3B698CB4,eUpHRV,1
3B698E91,sHeatPre,0
3B698E91,ePHPump,0
3B698E91,eSWPump,0

and


Code:
$ cat ~/Downloads/log.txt | od -xc
0000000      4233    3936    3938    3036    652c    5753    7550    706d
           3   B   6   9   8   9   6   0   ,   e   S   W   P   u   m   p
0000020      302c    000a    4233    3936    4338    3633    732c    6548
           ,   0  \n  \0   3   B   6   9   8   C   3   6   ,   s   H   e
0000040      7461    7250    2c65    0a31    4233    3936    4338    3633
           a   t   P   r   e   ,   1  \n   3   B   6   9   8   C   3   6
0000060      652c    4850    7550    706d    312c    330a    3642    3839
           ,   e   P   H   P   u   m   p   ,   1  \n   3   B   6   9   8
0000100      3343    2c36    5365    5057    6d75    2c70    0a31    4233
           C   3   6   ,   e   S   W   P   u   m   p   ,   1  \n   3   B
0000120      3936    4338    3442    ef2c    fe21    c3ff    ec38    2cef
           6   9   8   C   B   4   , 357   ! 376 377 303   8 354 357   ,
0000140      0a31    4233    3936    4338    3442    652c    5748    5052
           1  \n   3   B   6   9   8   C   B   4   ,   e   H   W   R   P
0000160      6d75    2c70    0a31    4233    3936    4338    3442    dd2c
           u   m   p   ,   1  \n   3   B   6   9   8   C   B   4   , 032
0000200      dd1a    c39d    e48c    2cc4    0a31    4233    3936    4338
         032 335 235     ** 344 304   ,   1  \n   3   B   6   9   8   C
0000220      3442    652c    6f44    6e77    5248    2c56    0a31    4233
           B   4   ,   e   D   o   w   n   H   R   V   ,   1  \n   3   B
0000240      3936    4338    3442    652c    7055    5248    2c56    0a31
           6   9   8   C   B   4   ,   e   U   p   H   R   V   ,   1  \n
0000260      4233    3936    4538    3139    732c    6548    7461    7250
           3   B   6   9   8   E   9   1   ,   s   H   e   a   t   P   r
0000300      2c65    0a30    4233    3936    4538    3139    652c    4850
           e   ,   0  \n   3   B   6   9   8   E   9   1   ,   e   P   H
0000320      7550    706d    302c    330a    3642    3839    3945    2c31
           P   u   m   p   ,   0  \n   3   B   6   9   8   E   9   1   ,
0000340      5365    5057    6d75    2c70    0030                        
           e   S   W   P   u   m   p   ,   0                            
0000351

thanks!

Last edited by bencpeters; 08-03-2011 at 09:49 PM.. Reason: wrong option on od...
# 5  
Old 08-03-2011
I can't reproduce your "tr" error. Please post the command typed an the complete error message.

There are certainly some weird characters in the second comma-delimited field of certain records in this sample data. There is also a weird trailing null character at the end of the first record.

What Operating System and version are you running?
What Shell do you use?
# 6  
Old 08-03-2011
Here's the tr error:


Code:
$ cat ~/Downloads/log.txt | while read old_line; do echo "${old_line}" | tr -dc '[0-9][A-Z][a-z],\n'; done
3B698960,eSWPump,0

3B698C36,ePHPump,1
3B698C36,eSWPump,1
tr: Illegal byte sequence
3B698CB4,3B698CB4,eHWRPump,1
tr: Illegal byte sequence
3B698CB4,3B698CB4,eDownHRV,1
3B698CB4,eUpHRV,1
3B698E91,sHeatPre,0
3B698E91,ePHPump,0

I'm running OS X 10.6.5, bash version 3.2.48
# 7  
Old 08-03-2011
My first guess would be that some locale-aware code in the underlying C library that tr is using does not approve of certain byte sequences. You could try running tr in the C/POSIX locale: LC_ALL=C tr ...

Regards,
Alister
This User Gave Thanks to alister For This Post:
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