linux - 如何检测linux机器上是否安装了tomcat和ant

Question

我正在尝试在我的 linux 机器上安装 Tomcat 和 Ant，但在安装它们之前我只需要检查它们是否已经安装。

关于tomcat:

我用谷歌搜索了很多，并在我的机器上的以下目录中搜索了 tomcat

/usr/local/, /opt/, /usr/share/

但是在上述路径中都没有找到tomcat文件夹，是否说明tomcat没有安装？所以实际上

1. what is the path to `look/find` exactly to know/check whether tomcat is installed or not in 
   all linux machines
2. what will be the path the tomcat will be installed exactly after installation
3. How to find the version of tomcat on any linux machine (if tomcat already installed) 
4. Whether there are any commands to look for both whether `tomcat` installed and `ant` 
   installed

关于 Ant :

我在谷歌上搜索并得到了以下命令，因此我在执行后得到了以下结果它

sh-4.2$ ant -v

结果

sh-4.2$ ant -v
Apache Ant(TM) version 1.8.2 compiled on November 21 2011
Trying the default build file: build.xml
Buildfile: build.xml does not exist!
Build failed

原来如此

1. Does the above result mean that `Ant` is installed ? or not ?
2. what is the path to `look/find` exactly to know/check whether ant is installed or not in 
   all linux machines
3. what will be the path the `ant` will be installed exactly after installation
4. How to find the version of `Ant` on any linux machine (if Ant already installed) 

Answer 1

一般情况下，您可以检查它们是否在 $PATH 上，如果它们不在 $PATH 上，请安装一个。

对于 Ant :

ant -v 代表冗长，ant -version 打印出它的版本。

   -help, -h
          print help on the command line options

   -projecthelp, -p
          gives information on possible targets for this project

   -version
          prints the version number and then exits ant

   -quiet, -q
          be extra quiet

   -verbose, -v
          be extra verbose

   -debug, -d
          print debugging information

   -emacs, -e
          produce logging information without adornments

   -logfile <file>, -l <file>
          use the given file to output log to

   -logger <classname>
          the class which is to perform logging

   -listener <classname>
          add an instance of the given class as a project listener

   -noinput
          do not allow interactive input

   -buildfile <file>, -file <file>, -f <file>
          use  the  given buildfile instead of the default build.xml file.
          This is the ant equivalent of Makefile

   -D<property>=<value>
          use value for the given property

   -keep-going, -k
          execute all targets that do not depend on failed target(s)

   -propertyfile <file>
          load all properties from file with -D properties  taking  prece-
          dence

   -inputhandler <class>
          the class which will handle input requests

   -find <file>, -s <file>
          (s)earch  for  buildfile  towards the root of the filesystem and
          use it

   -nice number
          A niceness value for the main thread: 1 (lowest)  to  10  (high-
          est); 5 is the default

   -nouserlib
          Run ant without using the jar files from ${user.home}/.ant/lib

   -noclasspath
          Run ant without using CLASSPATH

   -autoproxy
          Java 1.5+ : use the OS proxies

   -main <class>
          override ant's normal entry point

对于 tomcat:

如果 tomcat/bin 在 $PATH 变量上，version.sh 将打印出版本。