How can I see if a timestamp is before now or empty?-CodePudding

I'm trying to see if a timestamp is expired. Which it would be, if it's before now or empty.

exp=1662023095
NOW=$(date  %s)
if [[ -z $exp || (($exp < $NOW)) ]]; then
  echo "Update token..."
else
  echo "Token still valid!"
fi

The always echo "Update token...". Can someone tell me what I'm doing wrong?

CodePudding user response：

found in the man bash:

When used with [[, the < and > operators sort lexicographically using the current locale.

Give this a try (edited following the @user1934428 comment below)

if [[ -z $exp ]] || (( exp < NOW )) ; then
...

CodePudding user response：

The ((...)) doesn't make sense inside [[...]], but you can make it still simpler: If you write it without using $, i.e. as

if (( exp < NOW ))
then
  ...
fi

you don't need to test for an empty exp anymore, because exp would then be interpreted as if it were zero.

CodePudding user response：

You are setting the exp to old time: exp=1662023095 which is always less than the current time

date " %s"

Sample script:

cat "./73566778.sh"
#!/bin/bash
let exp=1662023095
echo "exp:      $(echo "scale=5;$exp / ( 60 * 60 * 24 * 365)" | bc -q) Years"
let NOW=$(date  %s)
echo "1662023095 seconds is always less than current second $NOW"
echo "NOW:      $(echo "scale=5;$NOW / ( 60 * 60 * 24 * 365)" | bc -q) Years"
echo "if [[ -z $exp ||  $exp -lt  $NOW ]]"
if [[ -z $exp ||  $exp -lt  $NOW ]]
then
        echo "Update token..."
else
        echo "Token still valid!"
fi

Output:

$ ./73566778.sh
exp:    52.70240 Years
1662023095 seconds is always less than current second 1662025519
NOW:    52.70248 Years
if [[ -z 1662023095 ||  1662023095 -lt  1662025519 ]]
Update token...

Hence this will always display: Update token...

Based on your comment:

I'm trying to see if a timestamp is expired. You have to write other script which is having exp data exp=... to update current script.