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decipher shell commands

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# 1  
Old 07-31-2012
decipher shell commands
Hi Guys,

I am busy trying to re-write a shell script that was written way back.

I need help with these codes:

Code:
# Process switches
if [ $? -gt 1 ] ; then
  echo "usage : process <optional instance>"
  exit 99
fi

What does the above code mean?

What does these $? -gt 1 mean?

Then I have these---

Code:
SIDA=true
SIDB=true

if [ $# -eq 1 ] ; then
  if [ $1 = "SIDA" ] ; then
    SIDB=false
  fi
  if [ $1 = "SIDB" ] ; then
    SIDA=false
  fi
fi

What does these mean?

What does $ mean in shell scripting and where can I learn more about using this in my scripts?

Thanks in advance....
Last edited by Scott; 07-31-2012 at 05:17 AM.. Reason: Code tags, please...
# 2  
Old 07-31-2012
Unix - Special Variables
# 3  
Old 07-31-2012
The $ sign expands (=replaces) parameters/variables to (with) their contents. 1, 2, ... are positional parameters, of which $# is the count; $? yields the exit code/status of your last command. Read the man page of your shell.
# 4  
Old 07-31-2012
Thanks for the replies...
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