The [c], I believe, is a character class containing only the letter c. If you wanted to match "cron" or "tron" you could use '[ct]ron'.
In this case, the only effect is that the ps output for the grep process won't match its own pattern, so you don't get the spurious item. ap ---------------------------------------------------------------------- Andrew J Perrin - [EMAIL PROTECTED] - http://www.unc.edu/~aperrin Assistant Professor of Sociology, U of North Carolina, Chapel Hill 269 Hamilton Hall, CB#3210, Chapel Hill, NC 27599-3210 USA On Mon, 8 Apr 2002, Johann Spies wrote: > In the grep's info page I find the following which works as said. But > I want to know why. What does the [c] do in this case? > > ------------------------ > 7. Why do people use strange regular expressions on `ps' output? > > ps -ef | grep '[c]ron' > > If the pattern had been written without the square brackets, it > would have matched not only the `ps' output line for `cron', but > also the `ps' output line for `grep'. > > ------------------------------- > > Johann > -- > Johann Spies Telefoon: 021-808 4036 > Informasietegnologie, Universiteit van Stellenbosch > > "Do not be anxious about anything, but in everything, > by prayer and supplication, with thanksgiving, present > your requests to God. And the peace of God, which > transcends all understanding, will guard your hearts > and your minds in Christ Jesus." Philippians 4:6,7 > > > -- > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] > > -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
