Category: cygwin

GNU/Linux userland tools for MS Windows

Recursively compare content of two directories

Command line

This requires the diff and vim packages.

diff --recursive /dir/ect/ory1 /dir/ect/ory2 > 1_vs_2.diff
vimdiff 1_vs_2.diff

Potentially useful diff options:

--ignore-all-space
--exclude=.svn

GUI

Install Intellij CE.

Then either Run IntelliJ Diff from the command-line.

Or from within a running Intellij window:

  • Open a common parent directory as a project
  • Select the two directories to compare
  • Right-click – Compare Directories

Alternatives

I often see the GPL-licensed WinMerge tool recommended, But it works only on Windows, last release was 2013 and navigation into sub-directories and file diffs is a bit clunkier than in Intellij.

Determine which Tomcat version is running

Determine process id

First we determine the process id(s) of the running Tomcat instance(s).

We can grep the running process list for ‘catalina.home’:

pgrep -f 'catalina.home'

This might yield more than one pid.

Or we can search by port (8080 is the default, adjust if necessary). The following commands will likely require root privileges:

lsof -t -i :8080

Alternatively, for example if lsof is not installed:

fuser 8080/tcp

Or yet another way, using netstat (or its “ss” replacement):

netstat -nlp | grep 8080

ss -nlp | grep 8080

Determine catalina.home

For the process id(s) determined above, we look at process details:

ps -o pid,uid,cmd -p [pidlist] | cat

For each specified pid, this shows the uid (system user) and the full command line of the process.

Typically the command line will contain something like “-Dcatalina.home=[path]” and that path is the catalina.home system property of the Java process.

Alternatively – with Java 7 and later – we can use the JDK command “jcmd” to query the JVM process for its system properties:

sudo -u [uid] jcmd [pid] VM.system_properties \
   | grep '^catalina.home' \
   | cut -f2 -d'='

Determine version

Now we can finally determine which Tomcat version is installed under the catalina.home path:

[catalina.home]/bin/catalina.sh version \
   | grep '^Server number:'

Note: Please replace [catalina.home] with the path you determined above.

The final output should be something like this:

Server number: 7.0.56.0

Compare two Tomcat installations using rsync

Lets assume you manage multiple servers that host Java web applications using the Tomcat web server.

To quickly compare the Tomcat installations on host1 and host2, we can use the “dry-run” mode of the rsync command.

In the following example, we assume that you have ssh access to both of your Tomcat hosts, the installations are in /opt/tomcat and the “tomcat” system user has read access to all relevant files and directories of the installation:

ssh tomcat@host1
rsync --archive --checksum --dry-run --verbose --delete \
      --exclude temp --exclude work --exclude logs --exclude webapps \
      /opt/tomcat/ tomcat@host2:/opt/tomcat/

This will list

  • All files that differ in checksum
  • All files that only exist on host2 (look for ‘deleting [filename]’)

Run the same commands with host1 and host2 switched, to also see the files that only exist on host1.

We excluded the temp, work and logs directories because they are variable in nature.
We also excluded the webapps directory because we only wanted to compare the base installation.

Fix Eclipse installation after Cygwin unzip

I used Cygwin’s unzip on Windows 7 to unpack freshly downloaded Eclipse zip packages. When trying to start eclipse.exe, I was getting weird error messages:

For Luna (4.4):

eclipse-luna-error-after-cygwin-unzip

For Mars (4.5):

eclipse-mars-error-after-cygwin-unzip

It turned out that after unzipping, the executable permission was not set on ‘exe’ and ‘dll’ files, so I had to fix it like this:

find eclipse \( -name '*.dll' -or -name '*.exe' \) -exec chmod +x {} \;

Human readable timestamp for filenames

I use this bash alias (should work in Linux, Cygwin, probably MacOS, maybe other Unixes):

alias timestamp="date --rfc-3339=ns | tr ' '  '_'"

Then use it like this for example to archive a file:

mv somefile somefile_$(timestamp)

You should see something like

`somefile' -> `somefile_2014-11-13_11:45:46.980175800-04:00'

If you don’t like colons in file names, change tr ' ' to tr ' :'.

Start script for stand-alone Java process

Directory structure

  • lib
    • some.jar
    • another.jar
    • …
  • config
    • dev
    • uat
    • …
  • start.sh
  • .setenv.sh

.setenv.sh

#!/bin/bash 

# environment (typically 'dev', 'uat' or 'prod') 
env=

# absolute path to java home ( >= 1.7 ) 
# such that $java_home/bin/java exists 
java_home=${JAVA_HOME} 

# add any additional environment setup here:

start.sh

#!/bin/bash 

# script should exit if any command fails 
set -e 

function envfail() { 
  echo $1; 
  echo "Please adjust $setenv_script and retry ..." 
  exit 1 
} 
function check_not_empty() { 
  if [ -z "$1" ]; then 
    envfail "Variable '$2' is unset or empty." 
  fi 
} 

script=$(readlink -f "$0") 
if [[ "$script" =~ .*[[:space:]].* ]]; then 
  echo "Script path contains spaces: $script" 
  echo "Please fix and retry ..." 
  exit 1 
fi 

# ok, now we know $script contains no spaces so 
# we don't need quoting acrobatics from here on 

dir=$(dirname $script) 
parent=$(dirname $dir) 
setenv_script=$parent/setenv.sh 

if [ ! -e $setenv_script ]; then 
  echo "$setenv_script not found" 
  cp $dir/.setenv.sh $setenv_script 
  envfail "Created a default $setenv_script for you." 
fi 
setenv_script_file=$(readlink -f $setenv_script) 
if [ -r $setenv_script_file ]; then 
  echo "Sourcing $setenv_script" 
  source $setenv_script 
else 
  envfail "Cannot read $setenv_script" 
fi 

check_not_empty "$env" 'env' 
config_env=$(readlink -f "$dir/config/$env") 
if [[ ! -r "$config_env" || ! -d "$config_env" ]]; then 
  envfail "Invalid env=$env : Cannot read directory $config_env" 
fi 

check_not_empty "$java_home" 'java_home' 
java="$java_home/bin/java" 
if [ ! -e "$java" ]; then 
  envfail "$java is not an executable file" 
fi 
java_version=$("$java" -version 2>&1 \
               | head -n 1 | cut -d'"' -f2 | cut -d'.' -f2) 
if [ $java_version -lt "7" ]; then 
  envfail "Java 1.7 or higher is required." 
fi 

# turn on bash debug output for the following lines 
set -x 

cd $dir 
mkdir -p "../log" 

nohup \ 
"$java" -cp "$config_env:lib/*" \
        net.doepner.example.Main \ 
        > "../log/example_stdout.log" 2>&1 &

Get java version string via shell commands

Determine the pure java version string from any Unix/Linux shell (including Cygwin):

java -version 2>&1 | head -n 1 | cut -d'"' -f2

This requires only the very commonly available and lightweight “head” and “cut” commands.

I originally found the one-liner on stackoverflow. Thanks to the friendly folks who shared it.

To get only the major version part (e.g. 8 for Java 1.8.x, 11 for 11.x), use this:

java -version 2>&1 \
  | head -1 \
  | cut -d'"' -f2 \
  | sed 's/^1\.//' \
  | cut -d'.' -f1

Note: The sed step is required for versions up to Java 8 that start with the “1.” prefix.

Example: Ensure Java 11 or higher:

#!/bin/bash

version=$(java -version 2>&1 \
  | head -1 \
  | cut -d'"' -f2 \
  | sed 's/^1\.//' \
  | cut -d'.' -f1 
)

if [ $version -lt "11" ]; then
  echo "Java 11 or higher is required."
  exit 1
fi

A minttyrc for black on white with red block cursor

I don’t particularly like the tradition of light text on dark backgrounds in everything that (shell) coders or Unix admins seem to use. But even the Jetbrains folks provide a Darcula theme now.

Anyway, I want more light in my mintty – which is the default Cygwin terminal – and an easy to find cursor:

oliver@windowsbox ~
$ cat .minttyrc 

BoldAsFont=yes
BoldAsColour=yes
BackgroundColour=240,220,180
ForegroundColour=0,0,0
CursorColour=255,0,0
CursorType=block
Black=0,0,0
BoldBlack=0,0,0
Red=160,0,0
BoldRed=80,0,0
Green=0,160,0
BoldGreen=0,80,0
Yellow=80,80,0
BoldYellow=40,40,0
Blue=0,0,160
BoldBlue=0,0,80
Magenta=100,0,60
BoldMagenta=50,0,30
Cyan=60,0,100
BoldCyan=30,0,50
White=60,60,60
BoldWhite=40,40,40
Font=Lucida Console
FontHeight=10

If you come across other colors that are too light to be readable on white background, just add more ColorName=0,0,0 lines in this file. Make sure you consult the related mintty reference documentation.

For existing work on more beautiful(?) but IMHO less ergonomic palettes of colors, you might want to check out these “Solarized” color configs for mintty.

Install and maintain Cygwin without Windows admin rights

Sometimes you work on Windows as a restricted user, without admin rights. Like many other good software packages, Cygwin can be installed anyway (see the respective FAQ entry).

These are the steps I used:

  1. Download setup-x86.exe (32bit) or setup-x86_64.exe (64bit).
  2. Run it with the “--no-admin” option
  3. During installation select the “wget” package
  4. Create /usr/local/bin/cygwin-setup.sh (for 32bit omit the “_64”): 
    #! /bin/sh
rm setup-x86_64.exe
wget http://cygwin.com/setup-x86_64.exe
chmod u+x setup-x86_64.exe
run ./setup-x86_64.exe --no-admin
  5. Make the script executable: 
    chmod ugo+x /usr/local/bin/cygwin-setup.sh
  6. Create a copy of the Cygwin terminal shortcut, rename it “Cygwin setup”
  7. Edit the shortcut target, replace 
    mintty.exe -i /Cygwin-Terminal.ico -

    with

    mintty.exe -i /Cygwin-Terminal.ico /bin/bash -l -c 'cygwin-setup.sh'

Whenever you want to run the Cygwin installer to install or remove packages, you can just execute the shortcut or run cygwin-setup.sh from the Cygwin command prompt.

Alternatively, you could also use the pure command-line tool apt-cyg.

Use standard bash for ssh login on shared hosts

Please note: The following instructions are for ssh logins on a remote host. The approach is not suitable for executing remote commands via ssh.

Problem

When you work on a remote Linux or Unix server (via ssh) you sometimes cannot control your login shell and/or its default config file. For example, you might be sharing the same user account on the server with other people or the use of the chsh tool might be locked down.

Maybe the default shell is something like ksh, or if bash is used maybe the .bashrc sets vi key bindings. This can be annoying if you are used to standard Linux bash with its default Emacs style bindings.

Suggested solution

In these cases you can do the following, assuming bash is installed and in the path on the host:

1) Create /usr/local/bin/sbash.sh (on Windows, use Cygwin).:

#! /bin/bash

 set -x

 if [ "$#" -gt 0 ]; then
   user_at_host="$1"
   shift
   ssh_options="$@"
 else
   set +x
   echo Usage: $(basename "$0") user@host [ssh-options]
   exit 1
 fi

 ssh -t $ssh_options \
        $user_at_host \
     "bash --rcfile .bashrc.for-remote-user-${USER}"

Make the file executable using something like chmod ugo+x /usr/local/bin/sbash.sh. You can then use it for remote logins like the ssh command, for example:

 
oliver@basement:~$ sbash.sh user@host

The $USER variable in the sbash.sh script will be substituted by the local shell with your local user name, which in this example is “oliver”.

2) On the host create ~/.bashrc.for_remote_user_USERNAME where USERNAME is the user name from the ssh client as mentioned above:

user@host$ vim $HOME/.bashrc.for-remote-user-oliver

Make sure this file name matches the –rcfile option in your ssh command.

You can then edit and use this file like a normal .bashrc file, i.e. for setting your favorite environment variables, bash options, aliases, etc.