----- Original Message ----- > Hello Dave, > > I have modified my patch. In my opinion, regular expression should not > mix with other task-identifying arguments, so I made some more > modifications Why not? It would be far more useful if you could maintain the current capability of providing a mixture of pid/task/name task-identifiers along with this new regular-expression-matching scheme. Dave > > At 2012-2-29 1:01, Dave Anderson wrote: > > > > > > ----- Original Message ----- > >> Hello Dave, > >> > >> The patch is used to add a new option, "-E regex", to perform the > >> command(s) on all commands whose names contains a match to "regex". > >> "regex" is interpreted as an POSIX extended regular expression. > >> > >> The new option is helpful when using to search some commands whose names > >> are similar. And I think it is more reliable than "foreach<name> > >> <command> | grep xxx", for information comes from command may have a > >> match to "xxx". > >> > >> P.S. > >> The patch uses some function defined in regex.h, which is offered by glibc. > > > > The concept is a pretty good idea. However: > > > > (1) It doesn't work as you've described it in the help page, and > > (2) I don't like the invocation, because option characters are > > meant to be passed to the selected command, and not for > > consumption by the foreach command itself. > > > > With respect to (1), your help page example shows this: > > > > crash> help foreach > > ... [ cut ] ... > > Display the state of tasks whose name contains a match to > > 'event.*': > > > > crash> foreach -E 'event.*' task -R state > > PID: 99 TASK: ffff8804750d5500 CPU: 0 COMMAND: "events/0" > > state = 1, > > > > PID: 100 TASK: ffff8804750d4ac0 CPU: 1 COMMAND: "events/1" > > state = 1, > > > > PID: 101 TASK: ffff8804750d4080 CPU: 2 COMMAND: "events/2" > > state = 1, > > ... > > > > But your example doesn't work with the encompassing "'" characters: > > > > crash> foreach -E 'event.*' task -R state > > crash> > > > > If I remove the encompassing "'" characters, it does work: > > > > crash> foreach -E event.* task -R state > > PID: 67 TASK: ffff88033833d500 CPU: 0 COMMAND: "events/0" > > state = 1, > > > > PID: 68 TASK: ffff88033833cac0 CPU: 1 COMMAND: "events/1" > > state = 1, > > > > PID: 69 TASK: ffff88033833c080 CPU: 2 COMMAND: "events/2" > > state = 1, > > > > PID: 70 TASK: ffff880338367540 CPU: 3 COMMAND: "events/3" > > state = 1, > > > > ... > > > > So apparently regcomp() does not handle strings encompassed with > > the "'" characters. > > > > With respect to (2), however, since the process name option already > > has the "\" invocation option to prevent ambiguity with the foreach > > command name: > > > > crash> help foreach > > ... > > name perform the command(s) on all commands with this name. If the > > command name can be confused with a foreach command name, then > > precede the name string with a "\". > > ... > > > > Perhaps there can be a third way of specifying the "name" option, where a > > regular expression *must* be encompassed by "'" characters, and therefore: > > > > (a) the argument can be recognized as a POSIX expression, and > > (b) the encompassing "'" characters can be stripped off before passing the > > argument string to regcomp(). > > > > So then you could simply enter: > > > > crash> foreach 'event.*' task -R state > > > > And have it described in the help page something like: > > > > crash> help foreach > > ... > > name perform the command(s) on all processes with this name. If the > > process name can be confused with a foreach command name, then > > precede the name string with a "\". If the process name is > > enclosed within "'" characters, then the encompassed string > > is a POSIX extended regular expression that will be used to > > match process names. > > ... > > > > Then you can simplify things by replacing the FOREACH_E_FLAG usage with > > a FOREACH_REGEX flag that can be set in cmd_foreach() and checked > > in foreach(). > > > > Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
