CODEWITHSUNDEEP
bashecho
C.Felix
C.Felix

Reputation: 1116

Bash echo variable in string always has spaces

I am currently working on a Mac OS X software update check script/plugin for Nagios, so that I can monitor my Mac Mini and Mac Pro machines, whether they have any updates available or not.

I created a variable called swUpdateCheck and assigned the check command to it, including some grep and awk, so that I can work with the output at the end. Since I don't always want to call the os update command, I just exported the output to a text file update.txt and am currently using the text file for building the final script.

This is my variable: 

swUpdateCheck=`cat update.txt | grep -B1 recommended | grep -v recommended | awk '{gsub(/^[[:cntrl:][:space:]]+|^\-+|\*\s/,"");}NF>0 1' | wc -l`

Content of the Text file:

   * Security Update 2018-004-10.12.6
--
   * Safari11.1.2Sierra-11.1.2
--
   * iTunesX-12.8

Now my issue is, that whenever I call the variable it scans through the file and should give me a number of lines at the end when I echo it. It does give me a number when using a simple echo but as soon as I combine the variable with a string, it adds spaces in front of the number and I don't understand why.

Normal echo of swUpdateCheck: 

$ echo $swUpdateCheck
3

Echo swUpdateCheck in a string: 

$ echo "There are $swUpdateCheck Updates available."
There are        3 Updates available.

What am I missing or doing wrong?

Upvotes: 0

Views: 2030

Answers (1)

KamilCuk
KamilCuk

Reputation: 141493

swUpdateCheck has spaces in it, not just 3. As you are not escaping the variable in echo $swUpdateCheck spaces get reinterpreted and 3 get's printed out. If you enclose the variable in ", as in echo ".... $swUpdateCheck ..." spaces will not be ignored. Observe the output with set -x:

$ set -x
$ echo
+ echo

$ swUpdateCheck="       3"  # assigment with spaces in it
+ swUpdateCheck='       3'
$ echo           3  # leading spaces get ignored
+ echo 3
3
$ echo $swUpdateCheck  # just printing '3', this is the same as above line
+ echo 3
3
$ echo "$swUpdateCheck"  # with "
+ echo '       3'
       3
$ swUpdateCheck=${swUpdateCheck// /}  # remove spaces using bash or use sed 's/ //g' or tr -d ' ' or other
+ swUpdateCheck=3
$ echo "$swUpdateCheck"   # now swUpdateCheck is without spaces, it will work
+ echo 3
3
$ echo "There are $swUpdateCheck Updates available."
+ echo 'There are 3 Updates available.'
There are 3 Updates available.

Upvotes: 2

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