read(1)read(1)NAMEread - read a line from standard input
reads a single line from standard input. The line is split into fields
as when processed by the shell (refer to shells in the first field is
assigned to the first variable var, the second field to the second
variable var, and so forth. If there are more fields than there are
specified var operands, the remaining fields and their intervening sep‐
arators are assigned to the last var. If there are more vars than
fields, the remaining vars are set to empty strings.
The setting of variables specified by the var operands affect the cur‐
rent shell execution environment.
Standard input to can be redirected from a text file.
Since affects the current shell execution environment, it is usually
provided as a normal shell special (built-in) command. Thus, if it is
called in a subshell or separate utility execution environment similar
to the following, it does not affect the shell variables in the call‐
recognizes the following options:
Do not treat a backslash character in any special way.
Consider each backslash to be part of the input line.
recognizes the following operands:
var The name of an existing or nonexisting shell variable.
determines the internal field separators used to delimit fields.
exits with one of the following values:
0 Successful completion.
>0 End-of-file was detected or an error occurred.
Print a file with the first field of each line moved to the end of the
while read-r xx yy
printf "%s %s \n" "$yy" "$xx"
done < input_file
SEE ALSOcsh(1), ksh(1), sh(1), sh-posix(1).