Michael, you are right and I feel like a fool. Of course - the regex was wrong!
But to meet you half way... the \s* matches the spaces the first time, and the [^0] matches the "1". After that, it replaces the 0 with a 1, and then you're 100% right. Doh! -Dan On Nov 19, 2010, at 5:50 PM, Michael Potter wrote: > On Sat, Nov 20, 2010 at 6:20 AM, <no-re...@cfengine.com> wrote: >> Forum: Cfengine Help >> Subject: replace_patterns bug? >> Author: babudro >> Link to topic: https://cfengine.com/forum/read.php?3,19347,19347#msg-19347 >> >> Hello Cfengineers. >> >> Like Michael Potter's post on 9 November, I am also running into some >> strange behaviour with replace_patterns. I wonder if someone can spot if I >> am doing something wrong so I don't file an erroneous bug report. >> >> All I am trying to do is replace a parameter line in a file. I created this >> rule to toggle the setting: >> >> >> bundle edit_line yum_plugins(x) { >> replace_patterns: >> "^enabled\s*=\s*[^$(x)]" replace_with => value("enabled = $(x)"); >> } >> >> >> The idea is that if I pass x=0 then it searches for "enabled" not equal to >> zero and, if it finds a match, changes it to be zero. >> >> When I run this promise, I get this: >> >> >> -> Promised replacement "enabled = 00000000000000000000" on line "enabled = >> 1" for pattern "^enabled\s*=\s*[^0]" is not convergent while editing >> /etc/yum/pluginconf.d/rhnplugin.conf >> Because the regular expression "^enabled\s*=\s*[^0]" still matches the >> replacement string "enabled = 00000000000000000000" >> Promise (version 8) belongs to bundle 'yum_plugins' in file './yum.cf' near >> line 215 >> -> Promised replacement "enabled = 00000000000000000000" on line "enabled = >> 1" for pattern "^enabled\s*=\s*[^0]" is not convergent while editing >> /etc/yum/pluginconf.d/rhnplugin.conf >> >> >> How weird is that? > > Replace patterns in continually evaluated until it reaches a state of > convergence, i.e. the pattern to be replaced no longer exists in the > file. It does not just stop after the first replace - this has always > been the case and is not new to 3.1.0. My issue report was that > insert_lines should not insert multiple times - this is new to 3.1.0. > >> >> I understand how "enabled = 00" does not match the pattern >> "^enabled\s*=\s*[^0]" since I only have a single zero, but how did it ever >> get that second >(and third and fourth &c.) zero? It should have made the >> first replacement and then stopped since the match is no longer true. > > How? First, you need to understand the regular expressions always > *attempt* to match. In your case, the \s* after the = matches nothing, > then the [^0] matches a space. Then that string is replaced with your > replacement pattern, hence you get an infinite loop of zeroed being > created. > >> >> If I put a dollar-sign at the end of the match string, it works. But I >> shouldn't have to do that. > > Actually, you do need to write your regex to ensure that it no longer > matches after the first replacement. Putting a $ at the end is one way > to do that, because now you are *forcing* the regex parser to compare > 0 to [^0] (which obviously doesn't match) - so the whole expression > doesnt match and the replace terminates. > > There are probably other ways you can write the regex to get the same > effect - but whatever you do it is your responsibility to ensure the > regex does not match after the replace_patterns is applied. > >> >> Am I missing something? >> >> Here is a self-contained policy file to demonstrate this apparent bug: >> >> >> body common control { >> bundlesequence => { "yum" }; >> } >> bundle agent yum { >> files: >> redhat:: >> "/tmp/test.conf" >> comment => "Demonstrate pattern bug", >> create => "false", >> edit_line => yum_plugins("0"); >> >> reports: >> plugins_toggled:: >> "Toggled 'enabled' flag in test.conf."; >> } >> bundle edit_line yum_plugins(x) { >> replace_patterns: >> "^enabled\s*=\s*[^$(x)]" replace_with => value("enabled = $(x)"); >> } >> body replace_with value(x) { >> replace_value => "$(x)"; >> occurrences => "all"; >> } >> >> # vim:ts=2 >> >> >> Create the file /tmp/test.conf with just this one line: >> >> >> enabled = 1 >> >> >> Now watch it explode: >> >> >> $ cf-agent -f ./pattern_bug.cf >> -> Promised replacement "enabled = 00000000000000000000" on line "enabled = >> 1" for pattern "^enabled\s*=\s*[^0]" is not convergent while editing >> /tmp/test.conf >> I: Made in version 'not specified' of './pattern_bug.cf' near line 18 >> Because the regular expression "^enabled\s*=\s*[^0]" still matches the >> replacement string "enabled = 00000000000000000000" >> Promise (version not specified) belongs to bundle 'yum_plugins' in file >> './pattern_bug.cf' near line 18 >> -> Promised replacement "enabled = 00000000000000000000" on line "enabled = >> 1" for pattern "^enabled\s*=\s*[^0]" is not convergent while editing >> /tmp/test.conf >> I: Made in version 'not specified' of './pattern_bug.cf' near line 18 >> Because the regular expression "^enabled\s*=\s*[^0]" still matches the >> replacement string "enabled = 00000000000000000000" >> Promise (version not specified) belongs to bundle 'yum_plugins' in file >> './pattern_bug.cf' near line 18 >> -> Promised replacement "enabled = 00000000000000000000" on line "enabled = >> 1" for pattern "^enabled\s*=\s*[^0]" is not convergent while editing >> /tmp/test.conf >> I: Made in version 'not specified' of './pattern_bug.cf' near line 18 >> Because the regular expression "^enabled\s*=\s*[^0]" still matches the >> replacement string "enabled = 00000000000000000000" >> Promise (version not specified) belongs to bundle 'yum_plugins' in file >> './pattern_bug.cf' near line 18 >> >> >> _______________________________________________ >> Help-cfengine mailing list >> Help-cfengine@cfengine.org >> https://cfengine.org/mailman/listinfo/help-cfengine >> > _______________________________________________ > Help-cfengine mailing list > Help-cfengine@cfengine.org > https://cfengine.org/mailman/listinfo/help-cfengine _______________________________________________ Help-cfengine mailing list Help-cfengine@cfengine.org https://cfengine.org/mailman/listinfo/help-cfengine
