text-file should contain AX.25 packets in the standard monitoring format or as a series two digit hexadecimal numbers. If the first number is 00 or c0, it will be treated as a KISS frame. If no file specified, data will be read from stdin.

M0XER-3>APRS63,WIDE2-1:!/4\;u/)K$O J]YD/A=041216|h`RY(1>q!(|

n2cma>APRS,TCPIP*,qAC,SEVENTH:@212127z43.2333n/77.1w_338/002g001t025P000h65b10208.wview_5_19_0

K0YTH-10>APNU3B,NULL,qAR,K0DMF-10:!4601.5NS09255.52W#PHG6360/W2,MNn 444.575

00 82 a0 ae ae 62 60 e0 82 96 68 84 40 40 60 9c 68 b0 ae 86 40 e0 40 ae 92 88 8a 64 63 03 f0 3e 45 4d 36 34 6e 65 2f 23 20 45 63 68 6f 6c 69 6e 6b 20 31 34 35 2e 33 31 30 2f 31 30 30 68 7a 20 54 6f 6e 65
+.fi

If  you  simply  fed  this  into decode_aprs, it would complain about the 
lower case in qA-something, added by the IGate, in the via path.  
We can take it out with something like this:

cat findu-errors.txt | sed -e 's/,qA.*:/:/' | decode_aprs

In the first case, we get,

Address has lower case letters. "n2cma" must be all upper case.

After changing the source address to upper case, there are other issues.  Identifying them is left as an exercise for the reader.

In the second example,

Invalid character in latitude.  Found 'N' when expecting 0-9 for hundredths of minutes.

Invalid character in longitude.  Found '9' when expecting 0 or 1 for hundreds of degrees.

In the third example,

Warning: Lower case letter in Maidenhead locator.  Specification requires upper case.

Digi2 Address, " WIDE2-1" contains character other than letter or digit in character position 1.