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Understanding of a script as a scripting newbie

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# 1  
Old 09-15-2009
Understanding of a script as a scripting newbie


I have the following script and do not understand part of it. I have a very little understanding of scripting.

The script is for Nagios to check the response of The guy who has written it is no longer in the company.


export PATH

. /adm/libexec/nagios/

print_help() {

print_usage() {


while test -n "$1"; do
  case "$1" in
      exit $STATE_OK
      exit $STATE_OK
      $ECHO "Unknown argument: $1"
      exit $STATE_UNKNOWN

rm -f $status_out
t=$(time 2>&1 -p wget --quiet --post-data='username=xxxxxx&password=xxxx&id=xxxxx' --no-check-certificate --output-document=$status_out --timeout=30 "https://${host}${url}" | perl -ne 'print int($1 * 1000) if /^real (\S+)/')

if [ ".$t" != . ]; then
  if [ -s $status_out ]; then
    if [ $t -ge $thresh_warn ]; then
    if [ $t -ge $thresh_crit ]; then

echo "REQUEST $result - $t ms | rtt=$t"
exit $exitstatus

What i don't understand are the following parts:

1. if [ ".$t" != . ]; then
I know that is a not equal check, but .$t and . ?

2. if [ -s $status_out ]; then
Here i don't know the meaning of -s

3. if [ $t -ge $thresh_warn ]; then
What does the -ge do here? I would expect something like $t -xy=xx

The check is delivering a status "Critical" and when i don't understand this three parts i can not verify the values which are delivered.



Last edited by locutus01; 09-15-2009 at 07:26 AM.. Reason: Tag failure
# 2  
Old 09-15-2009

1. if [ ".$t" != . ]; then

The above is basically to check whether the variable $t is set or not. If it is indeed set to some value, then ".$t" will NOT be equal to "."

eg: if $t is set to a, then ".$t" will be equal to ".a".

2. if [ -s $status_out ]; then

-s file True if file exists and has a size greater than zero.

"man test" will give you more information.

3. if [ $t -ge $thresh_warn ]; then

The above is checking whether $t is greater than or equal to $thresh_warn and hence "-ge" option.

This is used for comparing numerals.



# 3  
Old 09-15-2009
Thanks for the quick and good answer, will help me a lot.


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