Which environment variable indicates the internal field separator that is used by the parser?
IFS
Environment Variables
| Sr.No. | Variable & Description |
|---|---|
| 2 | HOME Indicates the home directory of the current user: the default argument for the cd built-in command. |
| 3 | IFS Indicates the Internal Field Separator that is used by the parser for word splitting after expansion. |
What’s the difference between while read and While IFs?
Apart from the (already clarified) IFS scoping differences between the while IFS=” read, IFS=”; while read and while IFS=”; read idioms (per-command vs script/shell-wide IFS variable scoping), the take-home lesson is that you lose the leading and trailing spaces of an input line if the IFS variable is set to (contain a) space.
What does IFS = read-R Line mean in Bash?
So when doing IFS= read -r line, what you are doing is setting IFS to an empty string (no character will be used to split, therefore no splitting will occur) so that read will read the entire line and see it as one word that will be assigned to the line variable.
Why do we set the IFS variable to an empty value?
So, in order to read each line literally, we need to make sure that no word splitting is going on. We do this by setting the IFS variable to an empty value. Note how we set IFS specifically for the duration of the read built-in. The IFS= read -r line sets the environment variable IFS (to an empty value) specifically for the execution of read .
Why is it not necessary to set IFS in Bash?
The changes to IFS only affect that statement, so that any following commands won’t be affected by the change. While the command is correct and will work as intended, setting IFS in this case is not might1 not be necessary. As written in the bash man page in the read builtin section :