bash while loop drops last line of text file [duplicate]

Question

when i cat this file I get 6 lines (it is a diff file)

bash-3.00$ cat /tmp/voo
18633a18634
> sashabSTP
18634a18636
> sashatSTP
21545a21548
> yheebash-3.00$

however when i read it line by line i only get 5 lines.

bash-3.00$ while read line ; do echo $line ; done < /tmp/voo
18633a18634
> sashaSTP
18634a18636  
> sashatSTP
21545a21548

or this

bash-3.00$ cat /tmp/voo | while read line ; do  echo $line ; done
18633a18634
> sashabSTP
18634a18636
> sashatSTP
21545a21548
bash-3.00$

i am missing the last line 'yhee' from the while loops.

Marc B · Accepted Answer · 2013-12-03 19:10:00Z

6

Note:

21545a21548
> yheebash-3.00$
      ^---- no line break

Your file doesn't terminate with a line break.

answered Dec 3, 2013 at 19:10

Marc B

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2 Comments

yo got it - the output is cron driven - i guess i will add an echo command to the last line.

You can also make the while loop run for the unterminated final line by using while read line || [ -n "$line" ]; do (see this previous answer).

Community · Accepted Answer · 2017-05-23 11:45:00Z

3

If you work with files which may or may not end up with a new line at end, you can do this:

while IFS= read -r line || [ -n "$line" ]; do
  echo "$line"
done <file

Or this:

while IFS= read -r line; do
  echo "$line"
done < <(grep "" file)

The second option solved a problem for me where the while loop was reading the same line multiple times in a CSV file. Thanks for the tip!