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https://issues.apache.org/jira/browse/HADOOP-8989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14025845#comment-14025845
]
Akira AJISAKA commented on HADOOP-8989:
---------------------------------------
Thanks for updating the patch. I compiled with the patch and tried some options.
1. When I executed -print0 option, newlines are included in the output as
follows:
{code}
# hdfs dfs -find /user/root -name '*.txt' -print0
abc.txt
def.txt
{code}
Newlines shouldn't be included in -print0 option.
2. In Find.java, spaces should be used instead of tabs.
{code}
// Initialize the static variables.
EXPRESSIONS = new Class[] {
// Operator Expressions
And.class,
// Action Expressions
Print.class,
// Navigation Expressions
// Matcher Expressions
Name.class
};
{code}
Minor nits:
3. In Expressions.java,
{code}
/**
* Returns the precendence of this expression
* (only applicable to operators).
*/
{code}
precendence should be precedence.
4. There are some trailing white spaces in Find.java.
5. In Print.java,
{code}
private Print(boolean appendNull) {
super();
setUsage(USAGE);
setHelp(HELP);
setAppendNull(appendNull);
}
private void setAppendNull(boolean appendNull) {
this.appendNull = appendNull;
}
{code}
can be simplified as
{code}
private Print(boolean appendNull) {
super();
setUsage(USAGE);
setHelp(HELP);
this.appendNull = appendNull;
}
{code}
6.
{code}
/**
* Construct a Print {@link Expression} with an operational ASCII NUL
* suffix.
*/
{code}
operational should be optional?
> hadoop dfs -find feature
> ------------------------
>
> Key: HADOOP-8989
> URL: https://issues.apache.org/jira/browse/HADOOP-8989
> Project: Hadoop Common
> Issue Type: New Feature
> Reporter: Marco Nicosia
> Assignee: Jonathan Allen
> Attachments: HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch,
> HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch,
> HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch,
> HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch
>
>
> Both sysadmins and users make frequent use of the unix 'find' command, but
> Hadoop has no correlate. Without this, users are writing scripts which make
> heavy use of hadoop dfs -lsr, and implementing find one-offs. I think hdfs
> -lsr is somewhat taxing on the NameNode, and a really slow experience on the
> client side. Possibly an in-NameNode find operation would be only a bit more
> taxing on the NameNode, but significantly faster from the client's point of
> view?
> The minimum set of options I can think of which would make a Hadoop find
> command generally useful is (in priority order):
> * -type (file or directory, for now)
> * -atime/-ctime-mtime (... and -creationtime?) (both + and - arguments)
> * -print0 (for piping to xargs -0)
> * -depth
> * -owner/-group (and -nouser/-nogroup)
> * -name (allowing for shell pattern, or even regex?)
> * -perm
> * -size
> One possible special case, but could possibly be really cool if it ran from
> within the NameNode:
> * -delete
> The "hadoop dfs -lsr | hadoop dfs -rm" cycle is really, really slow.
> Lower priority, some people do use operators, mostly to execute -or searches
> such as:
> * find / \(-nouser -or -nogroup\)
> Finally, I thought I'd include a link to the [Posix spec for
> find|http://www.opengroup.org/onlinepubs/009695399/utilities/find.html]
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