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https://issues.apache.org/jira/browse/HADOOP-9972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13773255#comment-13773255
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Colin Patrick McCabe commented on HADOOP-9972:
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Hmm. We could have a convenience method called {{listLinkStatus}} which just
called into {{listStatus}} with the correct {{PathOptions}}. I sort of lean
towards fewer APIs rather than more, but maybe it makes sense.
Shell globbing doesn't ignore all errors, btw.
{code}
cmccabe@keter:~/mydir> mkdir a
cmccabe@keter:~/mydir> mkdir b
cmccabe@keter:~/mydir> touch a/c
cmccabe@keter:~/mydir> touch b/c
cmccabe@keter:~/mydir> sudo chmod 000 b
root's password:
cmccabe@keter:~/mydir> ls */c
a/c
cmccabe@keter:~/mydir> ls b/c
ls: cannot access b/c: Permission denied
cmccabe@keter:~/mydir> ls
a b
cmccabe@keter:~/mydir> ls *
a:
c
ls: cannot open directory b: Permission denied
{code}
It's interesting that it ignores the error in the case of {{ls */c}}, but not
in the case of {{ls *}}. Hadoop's shell would abort (and give no results) in
both of those cases, which I think is suboptimal.
> new APIs for listStatus and globStatus to deal with symlinks
> ------------------------------------------------------------
>
> Key: HADOOP-9972
> URL: https://issues.apache.org/jira/browse/HADOOP-9972
> Project: Hadoop Common
> Issue Type: Improvement
> Components: fs
> Affects Versions: 2.1.1-beta
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
>
> Based on the discussion in HADOOP-9912, we need new APIs for FileSystem to
> deal with symlinks. The issue is that code has been written which is
> incompatible with the existence of things which are not files or directories.
> For example,
> there is a lot of code out there that looks at FileStatus#isFile, and
> if it returns false, assumes that what it is looking at is a
> directory. In the case of a symlink, this assumption is incorrect.
> It seems reasonable to make the default behavior of {{FileSystem#listStatus}}
> and {{FileSystem#globStatus}} be fully resolving symlinks, and ignoring
> dangling ones. This will prevent incompatibility with existing MR jobs and
> other HDFS users. We should also add new versions of listStatus and
> globStatus that allow new, symlink-aware code to deal with symlinks as
> symlinks.
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