Detect OS from Bash script and notify user

Question

Using bash, I want to find the operating system and notify the user. I tried:

OS='uname -s'
echo "$OS"
if [ "$OS" == 'Linux' ]; then
    echo "Linux"
else 
    echo "Not Linux"
fi

I just get

uname -s 
Not Linux

on the terminal, which is wrong. How do I correctly set the string to what uname returns?

Thanks

William Pursell · Accepted Answer · 2012-05-24 11:52:01Z

13

Rather than single quotes, you probably meant to use backticks:

OS=`uname -s`

but you really want

OS=$(uname -s)

Also, rather than an if statment, which will eventually become an if/else series, you might consider using case:

case $( uname -s ) in
Linux) echo Linux;;
*)     echo other;;
esac

answered May 24, 2012 at 11:52

William Pursell

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8 Comments

Graham Over a year ago

Thanks for the answer! That is the first time I've ever noticed the difference between a ` and a ' :D

chepner Over a year ago

That's just one reason $() is superior :)

William Pursell Over a year ago

@chepner. The quotes are not necessary, even if the output contains spaces. $() is a quoting mechanism, so putting it in double quotes is redundant. Consider: a='foo bar'; case $( echo foo bar ) in; $a):;; esac

Francis Litterio Over a year ago

$() only quotes when used immediately to the right of = in a variable assignment. Try /bin/ls $(date) to see the lack of quoting by $(). This probably doesn't affect the answer given above much, since uname -s almost always outputs a single word (without spaces).

jordanm Over a year ago

$() doesn't perform the quoting at all. Bash does not word-split on the right side of a variable assignment.

|

rjmoggach · Accepted Answer · 2014-10-22 06:20:08Z

2

This will return the OS as requested - note that uname is not necessarily available on all OSes so it's not part of this answer.

case "$OSTYPE" in
  linux*)   echo "linux" ;;
  darwin*)  echo "mac" ;; 
  msys*)    echo "windows" ;;
  solaris*) echo "solaris" ;;
  bsd*)     echo "bsd" ;;
  *)        echo "unknown" ;;
esac

edited Oct 22, 2014 at 6:20

answered Oct 15, 2014 at 2:09

rjmoggach

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3 Comments

tripleee Over a year ago

-1 There is nothing Bash-specific here but it also does not solve the OP's problem at all.

rjmoggach Over a year ago

his question says "Using bash, I want to find the operating system and notify the user" uname is not OS agnostic - it won't work on some OSes. This solution should work on bash on most. You're correct that it's not bash specific so i've adjusted the answer.

Alejandro Over a year ago

"$OSTYPE", distinguishes between android phones and full Linux installations.

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