from a pipeline, you can use a block {} to process the variable further. ie as a pipeline creates a subshell, the variable will not available elsewhere outside the block.
echo "hello world" | { read foo; echo foo=$foo; }
With stdin redirection < and process_substitution <(echo "bar") to get a generated input
read foo < <(echo "bar")
# The variable created is available in the same scope
echo foo=$foo;
from a string (<<< is a bash construct)
read foo <<< "Hello World"; echo foo=$foo;
from a file. Example: All lines in an array (where \c0 replicate the eof character thanks to backslash escape)
IFS=$'\n' read -r -a REPO_DIRS -d $'\c0' < /path/to/myfile.csv
Get the first two words (fields) of a line
Read parse the line with the IFS separators and assign the value to the names defined, we can then use it to parse a line.
Example
echo "hello world, how do you do ?" | { read foo bar mi; echo foo=$foo bar=$bar mi=$mi; }
foo=hello bar=world, mi=how do you do ?
tip: if you want to get rid of the command, add it as separator in IFS
echo "hello world, how do you do ?" | { IFS=" ," read foo bar mi; echo foo=$foo bar=$bar mi=$mi; }
-r Backslash does not act as an escape character. The backslash is considered to be part of the line. In particular, a backslash-newline pair may not be used as a line continuation.
-s Silent mode. If input is coming from a terminal, characters are not echoed.
-u fd Read input from file descriptor fd.
-t timeout Cause read to time out and return failure if a complete line of input is not read within timeout seconds. This option has no effect if read is not reading input from the terminal or a pipe.
-a aname The words are assigned to sequential indices of the array variable aname, starting at 0. aname is unset before any new values are assigned. Other name arguments are ignored. If no names are supplied, the line read is assigned to the variable REPLY.
-p prompt: Display prompt on standard error, without a trailing new- line, before attempting to read any input. The prompt is displayed only if input is coming from a terminal.
-n nchars read returns after reading nchars characters rather than waiting for a complete line of input.
-d delim: The first character of delim is used to terminate the input line, rather than newline.
names the names that will receive the output. See below name_assignment
Name assignment
The first word is assigned to the first variable name, the second word to the second name, and so on,
If there are :
more words than names, leftover words, and their intervening separators are assigned to the last name.
fewer words than names, the remaining names are assigned empty values.
The characters in IFS are used to split the line into words.
The backslash character (\) may be used to remove any special meaning for the next character read and for line continuation.