why empty line is not getting stored in variable

Question

I am using below code

    #! /bin/bash
for host in $(cat ./server.txt)
do 
    echo "$host"

done

server.txt contains :

     server1.com
     server2.com

     server3.com


     server4.com

But the above code is giving below output:

     server1.com
     server2.com
     server3.com
     server4.com

i.e its not taking account of empty lines.How can I fix that?

score 5 · Accepted Answer · answered Mar 29 '12 at 19:21

5

while read host; do echo "$host"; done < server.txt

With the code you provided, the file as a single string is given as the 4th argument to the for command. The shell then splits the string using arbitrary whitespace as a delimiter (assuming you have not altered the IFS variable).

answered Mar 29 '12 at 19:21

glenn jackman

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its not getting last line.i.e server4.com – Monojit Mar 29 '12 at 19:24
You could also set `IFS` first: `IFS="\n"` but I agree it's probably better to use `read`. – paulmelnikow Mar 29 '12 at 19:24
@grails_enthu, is your file missing a newline on the last line? – glenn jackman Mar 29 '12 at 19:27
@glenn got it.The last line also should be terminated by a new line.otherwise above script will ignore last line.* i saw your edit after my comment.thanks ;) – Monojit Mar 29 '12 at 19:34

johnshen64 · Answer 2 · 2012-03-29T20:01:00.647

1

empty lines are not there because they are considered whitespaces used to separate word values.

use this:

awk '{print $1}' server.txt

 server1.com
 server2.com

 server3.com


 server4.com

edited Mar 29 '12 at 20:01

answered Mar 29 '12 at 19:26

johnshen64

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1
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you mean "whitespace used to separate *words*" – glenn jackman Mar 29 '12 at 19:29
Printing is not the main concern here, I need to store values in variable. – Monojit Mar 29 '12 at 19:29
glenn. thanks, you are right. i meant to say values, not vars. i have now edited it. grails, thanks for pointing out the difference. i did not realize that you want the variable in the shell environment only. – johnshen64 Mar 29 '12 at 20:00

score 0 · Answer 3 · answered Mar 29 '12 at 21:38

0

Alternative

s=$(cat -E ./server.txt) 
while [ ${#s} != 0 ]
 do
  echo ${s%%\$*}
  s=${s#*\$}
 done

answered Mar 29 '12 at 21:38

pizza

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why empty line is not getting stored in variable

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