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I have a piece of code like this:

count=0
until [ -f $filename -o $count -ge 60 ]
do
  count=$((count+1))
  sleep 1
done

I know [ -f $filename -o $count -ge 60 ] is a test command, "-f $filename" tests if the file exists or not, "$count -ge 60" tests if count is greater than or equal to 60, what does "-o" mean?

I googled, can't find the answer, anyone can help?

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Try the help command for builtins: help test (help [ will tell you it's actually test). –  muru Sep 22 '14 at 18:53

2 Answers 2

up vote 1 down vote accepted

It's logical OR operator.

From bash documentation:

expr1 -o expr2
    True if either expr1 or expr2 is true.
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up vote 0 down vote

It is a logical or operation. The code checks if $filename exists once/second for 60 seconds.

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