How to pass lines from a file to a bash script, so that each line remains undivided, even if there are spaces?

Question

Given:

$ cat lines.txt
a/b
'c/d e/f'

$ cat 1.sh
#!/bin/sh
./2.sh `cat lines.txt`

$ cat 2.sh
#!/bin/sh
echo p1=$1
echo p2=$2
echo p3=$3

$ ./1.sh
p1=a/b
p2='c/d
p3=e/f'

How do I change lines.txt or 1.sh, so that 2.sh receives only two arguments:

• a/b
• c/d e/f

?

Answer 1

Set the IFS (internal field separator) to a newline:

$ cat 1.sh 
#!/bin/sh
OLD_IFS=$IFS
IFS="
"
./2.sh `cat lines.txt`
IFS=$OLD_IFS

$ ./1.sh
p1=a/b
p2='c/d e/f'
p3=

Answer 2

If you aren't locked into the idea of using cat to send as many args as the file is long, you may find this method quite flexible. You can pipe file directly to 2.sh

# echo -e "a/b\n'c/d e/f'" >lines.txt

fn2.sh() { set -f              # disable pathname expansion 
   while IFS= read -r line; do # -r prevents expansion of such things as \n
       printf "%s\n" "$line"   # printf is more robust than echo (when dealing with unknown data)
   done 
}
< lines.txt fn2.sh             # using redirection 

Answer 3

If your input file contains the line 'c/d e/f' and you want to process the item c/d e/f (without the quotes), then you may be looking for xargs. Its input format is a space-separated list of strings, with the characters ' and " delimiting literal strings. Also, \ makes the next character be interpreted literally, but only outside a string. For example, here's an input file:

how\'dy 'hello world' aaa\
bbb

The items in this file are how'dy, hello world and aaa␤bbb (where ␤ is a newline character).