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https://issues.apache.org/jira/browse/HDFS-245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12759212#action_12759212
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Robert Chansler commented on HDFS-245:
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A further thought (perhaps implied by Allen's remarks) is that there needs to
be a specification of Day Zero behavior for shell commands. I'm not opposed to
adding options separately. But on Day Zero, are links in command arguments
_always_ followed? Does *lsr* follow links? If so, how does *lsr* avoid loops?
*rmr*? And what about permissions for links? What is the moral equivalent of
lstat(2)? (From the lstat(2) man page: "Unlike other filesystem objects,
symbolic links do not have an owner, group, access mode, times, etc. Instead,
these attributes are taken from the directory that contains the link. The only
attributes returned from an lstat() that refer to the symbolic link itself are
the file type (S_IFLNK), size, blocks, and link count (always 1)."
A link is a name, and so should count against the _name_ quota, but not against
the _space_ quota.
*fsck* should never follow links. Nor is there any meaningful sense to whether
a link is "broken." When resolution is attempted, a link either resolves or it
doesn't.
> Create symbolic links in HDFS
> -----------------------------
>
> Key: HDFS-245
> URL: https://issues.apache.org/jira/browse/HDFS-245
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: 4044_20081030spi.java, designdocv1.txt,
> HADOOP-4044-strawman.patch, symlink-0.20.0.patch, symLink1.patch,
> symLink1.patch, symLink11.patch, symLink12.patch, symLink13.patch,
> symLink14.patch, symLink15.txt, symLink15.txt, symlink16-common.patch,
> symlink16-hdfs.patch, symlink16-mr.patch, symlink17-common.txt,
> symlink17-hdfs.txt, symLink4.patch, symLink5.patch, symLink6.patch,
> symLink8.patch, symLink9.patch
>
>
> HDFS should support symbolic links. A symbolic link is a special type of file
> that contains a reference to another file or directory in the form of an
> absolute or relative path and that affects pathname resolution. Programs
> which read or write to files named by a symbolic link will behave as if
> operating directly on the target file. However, archiving utilities can
> handle symbolic links specially and manipulate them directly.
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