Re:How not to test that mysqld is alive
by sjs on Monday October 05, 2009 @03:26PM
(#862547)
regex background: [abc] matches any of 'a', 'b', or 'c'. [m] matches only 'm'.
It works because the text to match is no longer included in the command line invoked to do the matching. Whether or not 'grep [m]ysqld' appears in the list produced by ps is irrelevant, as [m]ysqld does not match "m]ysqld". i.e. the 'm' matches, but then the match fails when it hits ']'.
tl;dr It's just a short way of matching "mysqld" without the matching pattern itself being "mysqld".
It works because the text to match is no longer included in the command line invoked to do the matching. Whether or not 'grep [m]ysqld' appears in the list produced by ps is irrelevant, as [m]ysqld does not match "m]ysqld". i.e. the 'm' matches, but then the match fails when it hits ']'.
tl;dr It's just a short way of matching "mysqld" without the matching pattern itself being "mysqld".