Bash - Read (Builtin Command) one line and assign variables

> Procedural Languages > Bash Shell and (Unix|Linux) Utilities (XCU)

1 - About

Read is a bash builtin command and read one line from the standard input, or from the file descriptor fd supplied as an argument to the -u option and assigned names.

The first word is assigned to the first name, the second word to the second name, and so on, If there are :

  • more words than names, leftover words and their intervening separators is 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.

Permits to read a csv ??

Advertising

3 - Syntax

read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d delim] [name ...]

where:

  • -e If the standard input is coming from a terminal, readline is used to obtain the line.
  • -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.

4 - Return code

The return code is zero, unless end-of-file is encountered, read times out, or an invalid file descriptor is supplied as the argument to -u.

Advertising