implement readLine using read

http://www.mitbbs.com/article_t/JobHunting/32042617.html

char *readLine() {
    int bufSize = 1024;
    static char *buf = malloc(sizeof(char) * (1 + bufSize));
    static int bytesAfterNewLine = 0;   // number of bytes left from last call
    static int lastpos = 0;             // where the leftover starts

    int totalBytes = 0; // total number of bytes in the array
    int foundLineBreak = 0;

    if (bytesAfterNewLine != 0) {
        memmove(buf, buf + lastpos, bytesAfterNewLine);
        totalBytes = bytesAfterNewLine;
        lastpos = 0;
    }

    while (true) {
        for (; lastpos < totalBytes; ++lastpos) {
            if (buf[lastpos] == '\n') {
                buf[lastpos] == '\0';
                bytesAfterNewLine = totalBytes - lastpos - 1;
                foundLineBreak = 1;
                lastpos = (last + 1) % bufSize;
                break;
            }
        }
        if (foundLineBreak) break;

        if (bufSize == totalBytes) {
            bufSize *= 2;
            buf = realloc(buf, bufSize + 1);
        }

        int bytes = 0;
        while (true) {
            bytes = read(buf + totalBytes, bufSize - totalBytes);
            if (bytes != 0) break;
        }

        if (bytes == -1) {
            buf[totalBytes] = '\0';
            break;
        }

        totalBytes += bytes;
    }

    if (totalBytes == 0 && foundLineBreak == 0) {
        return NULL:
    } else {
        return buf;
    }
}

How to delete the blank page after a table in Microsoft Word

This stupid and simple problem has been bugging me for ages!!! There is a simple workaround for me.
Select the blank paragraph, go to Font dialog, in tab "Font", select "Hidden", then the annoying blank page just disappears.

Note: if you turn on "Show paragraph marks and other hidden formatting symbols", the hidden text will be shown.

RabbIT

Enable filter rabbit.filter.ReverseProxy, by adding it to the front of httpinfilters value.
Configure values for sector rabbit.filter.ReverseProxy.

httpinfilters=rabbit.filter.ReverseProxy,rabbit.filter.HttpBaseFilter,rabbit.filter.DontFilterFilter,rabbit.filter.BlockFilter,rabbit.filter.RevalidateFilter
......
[rabbit.filter.ReverseProxy]
# This filter is not enabled by default, add it to httpinfilters if you want it.
# This Filter makes rabbit work as an accellerator for one web site.
# Change requests
transformMatch=^/(.*)
transformTo=http://<target_host>:<port>/$1

# Deny proxy requests, you probably want this.
# deny=^http(s?)://.*
deny=
# If we want to allow admin access.
allowMeta=true

Run RabbIT:

java -jar jars/rabbit4.jar -f conf/rabbit.conf
Resource: http://www.khelekore.org/rabbit/

Memory allocation settings in Hadoop

Edit file conf/mapred-site.xml to change amount of memory allocated to sorting:

<property> 
    <name>io.sort.mb</name>  
    <value>300</value>  
</property>

Edit file conf/mapred-site.xml to change amount of memory allocated to each map/reduce task:

<property>
    <name>mapred.child.java.opts</name>
    <value>-Xmx800m</value>  
</property>

Edit file conf/hadoop-env.sh to change amount of memory allocated to Hadoop daemons:

export HADOOP_HEAPSIZE=1000

Change ports used by Hadoop

Edit file conf/hdfs-site.xml to change ports used by HDFS

    <property>
        <name>dfs.secondary.http.address</name>
        <value>0.0.0.0:51090</value>
    </property>
    <property>
        <name>dfs.datanode.address</name>
        <value>0.0.0.0:51010</value>
    </property>
    <property>
        <name>dfs.datanode.http.address</name>
        <value>0.0.0.0:51075</value>
    </property>
    <property>
        <name>dfs.datanode.https.address</name>
        <value>0.0.0.0:51475</value>
    </property>
    <property>
        <name>dfs.datanode.ipc.address</name>
        <value>0.0.0.0:51020</value>
    </property>
    <property>
        <name>dfs.http.address</name>
        <value>0.0.0.0:51070</value>
    </property>
    <property>
        <name>dfs.https.address</name>
        <value>0.0.0.0:51470</value>
    </property>

Edit file conf/mapred-site.xml o change ports used by MapReduce

    <property>
        <name>mapred.job.tracker.http.address</name>
        <value>0.0.0.0:51030</value>
    </property>

    <property>
        <name>mapred.task.tracker.http.address</name>
        <value>0.0.0.0:51060</value>
    </property>

exclude directories when using GNU tar

tar zvcf name.tar.gz --exclude path/to/dir1 --exclude path/to/dir2 path/to/tar

Note:

1. Do not include a trailing '/' in the path of excluded directories.  Otherwise, it won't work.
2. Put --exclude before the directory/file to be tarred.

Install RPM packages with non-root account

Recently, I need to install RPM to RedHat Linux, but I don't have root access.  I found this post: http://ajaya.name/?p=6353.  However, some commands in the command are not correct or need more clarification.  So I wrote down my experience below.

• create file ~/.rpmmacros and add following line
      %_rpmlock_path lib/rpm/__db.000
• Initialize the database by running command:

rpm --initdb \

    --root /home/<user_name>/rpm-local/ \

    --dbpath /home/<user_name>/rpm-local/lib/rpm

• Check the dependence

rpm --root /home/<user_name>/rpm-local/ \
    --dbpath /home/<user_name>/rpm-local/lib/rpm \
    -ivh package.rpm

• Install package

rpm --root /home/<user_name>/rpm-local \
    --dbpath /home/<user_name>/rpm-local/lib/rpm \ 
    --relocate /usr=/home/<user_name>/rpm-local \
    --nodeps \
    -ivh package.rpm

Resources

• https://bugzilla.redhat.com/show_bug.cgi?id=222194
• http://www.redhat.com/archives/rpm-list/2007-May/msg00037.html
• https://rhn.redhat.com/errata/RHBA-2006-0440.html

Add "Edit with Vim" item to context-menu in Windows for Vim

This post shows how to add "Edit with Vim" and "Tab Edit with Vim" items to context menu (pop out when you right click a file) in Windows.

Run regedit.exe, go to HKEY_LOCAL_MACHINE/SOFTWARE/Classes/*/shell/

1. Create new key "Tab Edit with &Vim" (Right click parent entry -> New -> Key)
2. Create new key "Edit with Vim"
3. Create new key "command" under "Tab Edit with &Vim"
4. Edit the entry with name "(Default)", change its data to
   <vim_dir>\gvim.exe" -p --remote-tab-silent "%1" "%*"
5. Create new key "command" under "Edit with Vim".
6. Edit the entry with name "(Default)", change its data to
   <vim_dir>\gvim.exe "%1"

It seems that latest versions of vim automatically create the registry entry:

• HKEY_LOCAL_MACHINE\SOFTWARE\Vim\Gvim and the data of entry path points to the vim executable.
• HKEY_CLASSES_ROOT\*\shellex\ContextmenuHandlers\gvim. Data of the entry "(Default)" is the CLSID (51EEE242-AD87-11d3-9C1E-0090278BBD99).
  You can delete this entry because we have already added menu item "Edit with Vim".
• HKEY_CLASSES_ROOT\Applications\gvim.exe\shell\edit\command. Data of the entry "(Default)" is "<vim_dir>\gvim.exe" "%1"
• HKEY_CLASSES_ROOT\CLSID\{51EEE242-AD87-11d3-9C1E-0090278BBD99}
  It has a key named InProcServer32. The data of "(Default)" is <vim_dir>\gvimext.dll
• Some other keys

Logging in Hadoop

Hadoop uses log4j via Apache common logging.  The config file is conf/log4j.properties.

Some important variables are set in the command line.  Following is a snippet cut from the whole command line used to launch HDFS name node.

-Dhadoop.root.logger=INFO,DRFA
-Dhadoop.log.dir=/N/u/hdfs/programs/hadoop-0.21.0/bin/../logs
-Dhadoop.log.file=hadoop-hdfs-namenode-b009.log
-Dhadoop.home.dir=/N/u/hdfs/programs/hadoop-0.21.0/bin/..
-Dhadoop.id.str=hdfs

You can see that log dir, log file, log level, logger are set.  DRFA is defined in conf/log4j.properties.

pdf to eps conversion

Currently, I need to convert pdf files to eps so that they can be included in latex files.

1. Use Acrobat Pro open the pdf file. 
   Click File -> export -> PostScript -> Encapsulated PostScript or use "Save As" and change "Save As Type"
   However, the bounding box is NOT correctly calculated.
   You can use gsview to correct it.  Use gsview open the eps file, click "File -> PS to EPS", select "Automatically calculate Bounding Box" and save the output file.

2. Use ghostscript.  Execute following command:
   gswin32 -sDEVICE=epswrite -sOutputFile=<filename>.eps <filename>.pdf
   This works well and bounding box is correctly calculated.

3. Use Xpdf (http://www.foolabs.com/xpdf/download.html)
   pdftops -eps <filename>.pdf <filename>.eps
   However, the bounding box is NOT correctly calculated.