I have found myself using Vim as my Linux editor of choice.  It is not dependent on X11 being available and I can edit pretty much anything fairly quickly.  I have been using a Redhat flavored linux(Redhat,Fedora, Centos) for quite sometime and because I couldn’t guarantee that Emacs would be installed I just got used to using Vi.

When I first attempted to use Vi after using Emacs from my college days, I was initially very frustrated with modes and key sequences.  But after a very short time I found I could edit files very rapidly and make changes quite easily.

Quick key list:

1) The thing that I do quite often is to replace all Ctrl-M (Windows Returns) within a file.  (Yes, I could do this with a call to dos2unix, but this is a Vi list).   I found the following key sequence works quite well.

:%s/Ctrl-v<enter>//g

breaking this sequence down

2) Another sequence I use quite often is to reformat source code.

:1 <enter> <shift-v> <shift>-g =

breaking the sequence down

:1<enter>   – states go to the first line of the file

<shift>-v    – Turns on visual line mode which selects the entire current line

<shift>-g    -Makes the cursor go to the last line in the file and with the last command

selects the entire file

=                   – Tells the editor to reformat the selection area

This page will be updated as I figure out more useful commands. This is only a small amount of the power of VI!

I have had to process data files from customers that have come in as delimited files. The files are usually in CSV formats and the delimiters might change depending on the content of the files. Sometimes the delimiters are usually tabs”t”, pipes “|”, comma “,” or semi-colon “;”. A useful tool for processing this type of file is to use awk.

Example command line:

awk -F 't' '{OFS="|"; if (NR != 1) print $3,$2,$1}'

The ‘-F’ argument is followed by the character that you have the file separated on. The example above uses a tab escape sequence ‘t’ but you could have any character. One potential problem is if the data contains the same character that you are attempting to split on. As in a comma separated list using commas within a long text sequence.
The Second sequence of quoted text above starts the processing of the file. The if statement uses the NF keyword which stands for Number of Row. This tells the script that it should not fire for the first row. The print statement allows you to pick and choose the columns(numbered from 1) to use or allows you to reorder them.
The ‘OFS’ part of the command line that helps with the print statement describes the Output Field Separator. In the case above it is using a pipe character ‘|’ to separate the text as it is being printed out. This allows you comma separate the fields that you want instead of having to use a more sophisticated printf statement.

The input file is of the form

Label,name,address

And the output is going to be of the form:

address,name,Label

When I am writing build automation scripts, there are times that I have to insure that the previous command completed
with no errors. I have found that ERRORLEVEL gets filled in with the return value from a command.

dir %1

if (%ERRORLEVEL%) == (0) echo Found File: %1
if (%ERRORLEVEL%) == (1) echo Missing File: %1

So if you save the previous in a file and run the command with one (1) argument, it will display the output of the dir command
but also print either “Found file: ” or “Missing File: “.

Tags: DOS, scripting

The other day I had a requirement to fill in a date value while creating an entity in ClearQuest. The field that was required was a date and was formatted as “mm/dd/yyyy hh:MM::SS AM|PM”. I used the localtime function to return the date and used sprintf to format the date to the proper output.
The reason I used sprintf was that for hours, months and days less 10 the output was 1 digit instead of two and the input was not allowed. The %02d states that the digits used will be a minumum of 2 in this case.

Here is the sample program I wrote to test the expected output:

 my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime;

# formatted just by concatenating output
my $datestring = $mon . "/" . $mday . "/" . $year . "  " . $hour . ":" . $min.
":" . $sec  ;

# formatted using sprintf to ensure proper digit counts are output
my $datestring2 = sprintf("%02d/%02d/%04d %d:%02d:%02d %s",$mon,$mday,1900 +$yea
r,$hour,$min,$sec, $hour >= 12? "PM" : "AM");

 print $datestring;
  print $datestring2;

Tags: perl, scripting

Recently I was moving data between an old server and new web server. I had some 250 GB of data and thought about just using Secure Copy (scp). When I started the process, I walked away
thinking “No Problem”, but after a few files, I got an error due to file permissions and I did not want to figure out what files had not been copied yet or where to try to restart.
So I used rsync to mirror the drive. I was able to set it up and due to my slow network speed, it still took several days, but I was certain that I had gotten all the data.

rsync -azuv -e ssh  user@originserver:public_html/* public_html/

The options I used were for :

This took some time to run, but I did not have to babysit the command and it duplicated the data from my old server to the new one.

I was writing a batch file the other day and needed to change the argumets to a command based on if the user had specified his password on the command line.

SET PASS=somepassword
: or
:SET PASS=
if x%PASS%= X (
  SET PASSARG=--password somepassword
) else
(
  SET PASSARG=
)

commandtorun %PASSARG%

Now if the user comments out his password, the script will make the PASSARG environment variable be empty or if they set a password the passarg variable will be filled in.

Tags: DOS, scripting

In each language that I have learned I have found it useful to know how to process command line arguments and here is a simple framework that I use for Java. I usually wrap the java command line in a bat or shell file to make it easier to run so that the user does not have to worry about classpath or path issues.

The following is the basic code to handle the command line arguments.

class CmdArgs
{

  public static void main(String[] args)
  {
      int argsize = args.length;
      String curarg;

      if (argsize > 0 )
      {
       
      }
      
      for(int i = 0; i < argsize; i++)
      {
          if (args[i].equals("--host"))
          {
             i++;
             host = args[i];
           }
          else if (args[i].equals("--debug"))
          {
               debug = 1;
          }
          else
          {
              System.out.println("Unknown option: " + args[i]);
              System.exit(1);
          }
       }

   }
}

The bat file for Dos/Windows might look like this:

@echo off

java -cp c:javabin;somejar.jar  com.etechtips.CmdArgs %*

The shell based file might look like:

java -cp /home/ecdown/javabin:somejar.jar com.etechtips.CmdArgs $*

Tags: Java, Scripts

I use find and grep quite a bit. I found that I was regularly searching for strings in file and was typing commands like:

find . -exec grep "somestring" {} ; --print

This find command will search from the current directory and for each file will run grep on it and if it finds a matching string, it will print the string and then the filename. So I took this and moved it into a script.

#!/bin/sh

if [ $# -lt 1 ]; then
  echo 1>&2 Usage: $0 ""
  exit 127
fi
icase=
search=

while [ $# -ge 1 ]; do
  case $1 in
     -i) icase=$1;;
      *) search=$1 ;;
  esac
  shift
done

find . -type f -print0 | xargs -0 grep $icase $search

This allows me to run a command such as

ffind -i Super

This command will search all file names starting from the current directory and recurse directories and the “-i” will tell it to ignore case.

Tags: scripting

There are times that I get on a Linux box and want to know about some of the resources available to me. There are tools that can accomplish this, but there are some files that contain basic settings about the resources available to the system. One of those file is:

/proc/cpuinfo

This file contains information about the Processors and you can do a simple:

more /proc/cpuinfo

to see all the details or you can grep for certain fields:

processor       -- This will show you how many processor entries there are.
cpu MHz  or MHz -- This will show you the speed of the processors.
cache size      -- This will show you the cache size available to the processor.
model           -- This will show you the type and model of the processor you are using.

There are quite a few more fields, but these are the ones that I check the most.

Tags: Linux, processor, Utilities

When I am editing and having a “clumsy fingers” day, I find that I have to reload the file that I am editing from disk repeatedly. I usually just do a quick “:q!” and re-run the vi command that opened the file. But there is a better way!

Use the :edit command:

:edit

Or you can shorten it to

:e

Now if you have typed in the window you are editing and want to reload from disk anyway without saving, remember to add the exclamation point(!) to the command.

:edit!

or

:e!

Tags: editors, utilitie, vi