Shell Scripting - check java bin

On a unix machine,开发者_Go百科 how can I write a shell script for checking if 'java bin' directory has been included in $PATH env. variable?

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It's probably simplest to use which:

which java || exit 1

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if which java >/dev/null 2>&1 ; then
  echo yes
fi

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Since the directory name can be anything, this would be a bit hard to check by looking at the $PATH variable, but you could try looking at the return value of a command like which javac.

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which is appropriate, but only checks for your command defined in $PATH. What if javac is not defined in $PATH but it is installed somewhere else? In that extreme case, you use find or locate to find where javac is.