Testing for a Specific Error Level in Batch Files

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Summary

The Microsoft MS-DOS "IF ERRORLEVEL <number>" statement checks for error levels of the given number or greater. If you want to check for a specific error level, you should use the following command construct


IF ERRORLEVEL <N> IF NOT ERRORLEVEL <N+1> <COMMAND>
where <N> is the desired number. The <N+1> portion of the command must be calculated as the command is entered, because the MS-DOS command interpreter cannot perform mathematical calculations.

More Information

The nested IF statements allow specific selection of an error level because the NOT operator effectively reverses the inequality. The command


IF ERRORLEVEL 5 ...
is equivalent to the algebraic construct


IF E = 5 OR E > 5 THEN ...
while the command


IF NOT ERRORLEVEL 6
is equivalent to the algebraic construct:


IF E < 6 THEN ...
The combination of the two IF commands works as described because the second IF is executed only if the first is true, and the <command> is executed only if the second is true; therefore, the combination of the two commands is executed only if BOTH are true. Because the desired error level is bracketed with the two tests, the entire conditional is TRUE only when ERRORLEVEL is exactly that value.


This same syntax can be expanded to cover a sequential range of ERRORLEVEL return codes by increasing the difference between the values checked for.
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ID článku: 69576 – Posledná kontrola: 16. 11. 2006 – Revízia: 1

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