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Editorial Team
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Asked: 2026-05-15T05:10:37+00:00

I’m banging my head against a wall with a regular expression. I’m trying to

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I’m banging my head against a wall with a regular expression. I’m trying to define an expression that excludes exactly this text ‘System’ (case insensitive), but can contain
the word ‘System’ providing it’s not just that.

Examples:

  • System == INVALID
  • SYSTEM == INVALID
  • system == INVALID
  • syStEm == INVALID
  • asd SysTem == Valid
  • asd System asd == Valid
  • System asd == Valid
  • asd System == Valid
  • asd == Valid
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1 Answer

  1. Editorial Team

    Try this:

    ^(?!system$)

    Or this to match the whole line:

    ^(?!system$).*$

    The regex has a negative look-ahead on its beginning, which doesn’t match if “system” is the entire string.

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