BASH: Read entire file line in for loop

crts · 06-01-2010, 03:28 AM

Quote:

Originally Posted by cioraneanu

Having problems with reading from file. This is my script.

Code:

nr=0
cat lista_ip.txt | while read a
do

if [ xxx]
then

echo "yyyyyyyy"
nr=$(($nr+1))
echo "NR=$nr"
fi

done

echo "NR=$nr"

It does what i needed, counts the number of lines but after it exits the while no values were saved. My $nr variable is back to 0 in the end. Any ideas?

Hi,

the problem is that the pipe is executed in a subshell. Therefor changes made in a subshell are not visible in the parent shell. Here is more info on that matter:
http://mywiki.wooledge.org/BashFAQ/024

PS: Please read also pixellany's post one prior to yours and do not post in old threads.

xiaodown · 04-18-2013, 12:06 PM

Sorry to necromancer this thread; however, it is the top search result on Google from linuxquestions.org for 'read whole line bash'.

So, in the interest of helping out googlers, like myself, I'm going to post the solution to this here. This will hopefully help others, but mainly, it will help me the next time I forget how to do this and I consider changing my IFS.

Given a file with lines that contain spaces, such as this:

Code:

[user@box ~]$ cat blah
thislinehasnospaces
this line has spaces
these
are
separate
lines
This is another line with a variety of spaces

you can read in whole lines using "read -r", thusly:

Code:

[user@box ~]$ while read -r sillyvariable; do echo "$sillyvariable"; done < blah
thislinehasnospaces
this line has spaces
these
are
separate
lines
This is another line with a variety of spaces

So, there it is.

Again, sorry to necro the thread.