Read the first word on a specific line from a text file using batch script then feed into an if statement - batch-file

Question

Sorry I know similar things have been asked here but basically I'm trying to read a text file within a batch script and evaluate what has been written to the file.
The job is a print job that sends a file to a printer, I have it echoing the output from the command to a log file. I then want to read in what the output was and if there was an error I will then send an email so we know when things stop working.
It always appends to the end of the file so I know if there's an error the 4th from last line will begin with "Error:". So my question is how can I read that in to a variable so I can perform an IF statement. I've got the emailing part sorted it's just reading from the file that I'm struggling with.
Any help would be much appreciated. Here's an example of the content of the file when there's an error:
----
C:\XG1\DGS01\prints\000000398200001.XG1
19/03/2013
15:02
1 file(s) copied.
Error: print server unreachable or specified printer does not exist.
1 file(s) moved.
It leaves one blank line at the end of the file so I'm going with the last line minus 4.
Thank you

Answer 1

as a line in your batch file:
for /f "tokens=1*delims=:" %%i in (thenameofyourfile) do if "%%i"=="Error" set message=%%j
echo message was "%message%"
Actually, that will report if ANY lines are in the format you describe.
#ECHO OFF
SETLOCAL
(SET message=)
FOR /f "tokens=1,2*delims=[]:" %%i IN (
' TYPE thenameofyourfile^|find /n /v "" '
) DO (
SET lastline=%%i
IF "%%j"=="Error" SET errorline=%%i&SET message=%%k
)
SET /a target=%errorline% + 3
IF %target% neq %lastline% (SET message=)
IF DEFINED message ECHO error found %message%
should get the line ONLY if it's the fourth last line in the file - the "+ 3" being the line-count required (well, minus 1)
BUT - remember that if this is, as it seems, a log file that it's possible (I'd imagine) that further entries may appear AFTER the error (for further jobs) so the target for the Line beginning "Error:" may not be the fourth-last...
OTOH, using the line(s) I first posted, once an "Error:..." line appears, it will be detected EVERY time - you'd need to reset the logfile in your mail-send procedure (save existing & recreate empty?)

Answer 2

Solution without any loop (does test if any error):
#findstr Error: printer.log >nul 2>&1
#if %errorlevel% equ 0 echo Send email now!
And this code does only test the fourth line before the last line for an error:
#echo off &setlocal enabledelayedexpansion
for /f %%i in ('findstr /n "^" printer.log') do (
set line4=!line3!&set line3=!line2!&set line2=!line1!&set line1=%%i)
echo %line4%|findstr Error: >nul 2>&1
if %errorlevel% equ 0 echo Send email now!

Answer 3

If you want to start reading the fourth line from the bottom of your log file, you can count the number of lines in your log file, subtract 4, then more +%count% to get the tail of the log.
#echo off
setlocal
set logfile=printerlog.log
for /f "tokens=2 delims=:" %%I in ('find /c /v "" "%logfile%"') do set lines=%%I
set /a "tail4=%lines% - 4"
for /f %%I in ('more +%tail4% "%logfile%" ^| find /i "Error:"') do (
rem do your email voodoo here
)
If your log file will exceed 65,535 lines, I recommend looping through the file using JScript or VBScript instead of a batch loop. Skipping that many lines with more will cause more to crash, so you'd have to loop line-by-line and increment a counter. However, batch for loops are terribly slow.
Here's the same script that replaces more with JScript-ish file reading.
#if (#a==#b) #end /*
:: batch portion
#echo off
setlocal
set logfile=printerlog.log
for /f "tokens=2 delims=:" %%I in ('find /c /v "" "%logfile%"') do set lines=%%I
set /a "tail4=%lines% - 4"
for /f "delims=" %%I in ('cscript /nologo /e:jscript "%~f0" %tail4% "%logfile%" ^| find /i "Error:"') do (
rem do your email voodoo here
rem %%I contains the matching line.
rem After one match, stop processing further
goto :EOF
)
goto :EOF
::JScript portion */
var i=0, fso = new ActiveXObject("Scripting.FileSystemObject").OpenTextFile(WSH.Arguments(1),1);
while (!fso.AtEndOfStream) {
if (i++ < WSH.Arguments(0)) fso.SkipLine();
else WSH.Echo(fso.ReadLine());
}
fso.Close();

Answer 4

I believe the fastest and least resource-intensive way to check for errors is with GNU tail. If you can, get the .zip binaries and put tail.exe in your path or where your batch script can access it. Then:
#echo off
setlocal
tail -n 4 printerlog.log | find /i "Error:" >NUL && (
echo Error found. Sending email.
rem do email stuff
)
Or if you wish to capture the text of the error for your email:
#echo off
setlocal
for /f "delims=" %%I in ('tail -n 4 printerlog.log ^| find /i "Error:"') do (
echo Error found: %%I
rem do email stuff
goto :EOF
)
tail is much more efficient than all these other methods of counting the number of lines in the log file and looping through the log file line-by-line, whether looping in batch or in JScript.