Read fields separated by zero
Given this file
printf 'alpha\0bravo\0charlie' > delta.txt
I would like to read the fields in separate variables. The reason I use the null separator is because the fields will contain paths to files that can contain any character other than null. I've tried these commands:
IFS= read mike november oscar < delta.txt
IFS=$'\0' read mike november oscar < delta.txt
However, the fields will not split correctly
$ echo $mike
alphabravocharlie
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The assignment IFS=$'\0'
does not make the null character a delimiter, as Bash variables cannot contain null characters . IFS=$'\0'
is equivalent IFS=
, which you can check by doing:
bash-4.3$ IFS=$'\0'
bash-4.3$ echo ${#IFS}
0
And IFS=
by definition means that the word doesn't break at all (see the Bash Reference Manual ).
What you can do is read the null-delimited elements one at a time using the -d
read
builtin option . According to the linked documentation,
-d delim
The first character is
delim
used to terminate an input line, not a new line.
We can use an empty string delim
to get the desired behavior.
Example (I took the liberty of adding a space to your example to demonstrate how it achieves what I want - no spaces are separated):
bash-4.3$ printf 'alpha with whitespace\0bravo with whitespace\0charlie with whitespace' > delta.txt
bash-4.3$ { read -r -d '' mike; IFS= read -r -d '' november; IFS= read -r -d '' oscar; echo $mike; echo $november; echo $oscar; } < delta.txt
alpha with whitespace
bravo with whitespace
charlie with whitespace
I also use an option -r
to keep backslashes in the input file. Of course, you can replace < delta.txt
with cat delta.txt |
at the beginning.
I know reading one by one is annoying, but I can't think of anything better.
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