Re: How to make `read` fail if there is not enough fields in the input?

[Assaf Gordon]

On 2019-12-04 8:01 p.m., Eli Schwartz wrote:
> On 12/4/19 9:12 PM, Peng Yu wrote:
> > I’d like to know whether there is enough field in a TSV row.
>
> Are you building a TSV validator in bash? o_O

Somewhat related:

GNU Datamash ( https://www.gnu.org/software/datamash/ )
has a "check" command that performs exactly that:
verifies that an input file for number of fields.

Examples:

  $ printf "A\tB\t\C\n" | datamash check
  1 line, 3 fields


  $ printf "A\tB\tC\nD\tE\n" | datamash check
  line 1 (3 fields):
    A   B       C
  line 2 (2 fields):
    D   E
  datamash: check failed: line 2 has 2 fields (previous line had 3)

Use "-W" if the delimiters are whitespace (and not a single tab):

  $ printf "A\tB \t C\nD    E F\n" | datamash -W check
  2 lines, 3 fields

The exit code will be zero (success) if the file has
same number of fields in all lines.

More details and examples of incorporating it in scripts here:
  https://www.gnu.org/software/datamash//manual/html_node/Check.html


regards,
 - assaf


disclaimer: I'm datamash's developer :)