Nostalgic Java Tools

Overview

Package mdvl-java-nostalgic-tools provides a few Ma_Sys.ma Tools that are included in MDVL for nostalgia only, because their functionality is provided by other, and well-maintaned tools. Still, the tools are very simple and run on Windows as well as Linux which does not always hold for their better counterparts.

Compile all tools (requres Ant and a JDK) by running

$ ant

Package them together (on Debian systems with suitable depnendencies installed) by running

$ ant package

The following sections describe the individual tools in man-page style.

cmdcolors

Name

cmdcolors – Display color capabilities of the console (max 16 colors)

Synopsis

cmdcolors

Description

Outputs a table with certain useful ANSI escape sequence colors. Does not display all possible combinations but some that are considered most useful.

See also

colortest-16b(1) – does the same thing but better in all regards: The output is less convoluted and it reminds the user of the correct escape sequence syntax.

netread

Name

netread – Listen to data incoming on sockets and display it in hex.

Synopsis

netread [port]

Description

Listens on the specified port by using a socket. Whenever data comes in, it prints them out in HEX. Once the connection closes, a new socket is created.

The default port is 5971 unless otherwise specified.

Example

Open a terminal and run netread:

$ netread
NetRead 1.0, Copyright (c) 2012 Ma_Sys.ma.
For further info send an e-mail to Ma_Sys.ma@web.de.

Listening on port 5971
Press enter to terminate application.

 68  65  6c  6c  6f  20  77  6f  72  6c  64  0a                                  hello.world.

 6e  65  77  20  77  6f  72  6c  64  0a                                          new.world.

In another terminal, send some messages:

$ echo hello world | nc 127.0.0.1 597
$ echo new world | nc 127.0.0.1 5971

See also

nc(1), xxd(1) and the shell together do the same:

$ while true; do nc -l 5971 | xxd; echo; done
00000000: 6865 6c6c 6f20 776f 726c 640a            hello world.

00000000: 6e65 7720 776f 726c 640a                 new world.

version_change

Name

version_change – Compute checksums of a directory’s files to detect changes.

Synopsis

version_change display DATABASE DIR
version_change accept  DATABASE DIR

Description

This tool recursively computes the SHA-256 checksums of all files found below directory DIR and stores them in a CSV file DATABASE when invoked with accept.

When invoked with display, it will compute all the checksums and based on that, output a list of files that were either added, changed or removed.

Bugs

• version_change not use java.nio API for traversal and is thus prone to endless loops in the presence of symlinks, mount points etc.
• After displaying the changes, accepting them takes another complete run that needs to compute all the checksums. This is highly inefficient!

See also

find(1), sort(1), diff(1), sha256sum(1)

Combine them as follows:

# accept
find . -type f -exec sha256sum {} + | sort > state_old.txt
# display
find . -type f -exec sha256sum {} + | sort > state_new.txt
diff state_old.txt state_new.txt
# accept (without recomputation!)
mv -f state_new.txt state_old.txt

If cut and paste are added to swap the columns in the state_ files, it behaves even more like version_chnage in that it will become possible to detect the difference between changed and added/deleted files.

visual_copy

Name

vcp – Copy directory trees while displaying a lot of progress info

Synopsis

vcp SRC DST

Description

Copies directory SRC to DST. Two modes of invocation are to be distinguished:

• If SRC ends on a trailing slash (e.g. /root/), then its contents are put directly below DST.
• If SRC does not end on a trailing slash (e.g. /root), then a directory with the same name as SRC is created below DST and data is copied like with cp -R SRC DST.

During Invocation, vcp displays a lot of progress information. Some of the ideas (speed diagram) have been taken up by Windows 10’s copy function while others (progress bars separate for number of files and data) are quite uncommon.

Visual Copy does not retain any file attributes nor modification times.

Exit Status

1	failed to list some directories or incorrect commandline options
2	failed to copy some files
64	Bug

See also

rsync(1) – does everything better except for the progress bars.

# Command to replace
vcp /root/ /tmp/test

# Very reliable, works efficiently over netcat to transfer large
# structures. No resumption upon interruption.
tar -C /root -c . | pv | tar -C /tmp/test -x

# Slightly slower (?) than tar, but allows resuming the transfer
# and displays the names of the files as transferred
rsync -av /root/ /tmp/test/

xmlparser

Name

xmlparser – Commandline tool to parse XML files with Java

Synopsis

xmlparser FILE

Description

This program attempts to parse the given XML file using a SAXParser that is validating and XInclude aware. In case of invalid files, the exception is printed to console, otherwise no output is shown.

See also

xmlstarlet(1) which can provide a similar use with xmlstarlet validate.