Read last line of file in bash script when reading file line by line [duplicate]

Answer 1

Your problem seems to be a missing carriage return in your file.

If you cat your file, you need to see the last line successfully appearing before the promopt.

Otherwise try adding :

    echo "Reading "$currentJob
    echo >> $currentJob #add new line
    while read line; do

to force the last line of the file.

Answer 2

It sounds like your input file is missing the newline character after its last line. When read encounters this, it sets the variable ($line in this case) to the last line, but then returns an end-of-file error so the loop doesn't execute for that last line. To work around this, you can make the loop execute if read succeeds or it read anything into $line:

...
while read line || [[ -n "$line" ]]; do
    ...

EDIT: the || in the while condition is what's known as a short-circuit boolean -- it tries the first command (read line), and if that succeeds it skips the second ([[ -n "$line" ]]) and goes through the loop (basically, as long as the read succeeds, it runs just like your original script). If the read fails, it checks the second command ([[ -n "$line" ]]) -- if read read anything into $line before hitting the end of file (i.e. if there was an unterminated last line in the file), this'll succeed, so the while condition as a whole is considered to have succeeded, and the loop runs one more time.

After that last unterminated line is processed, it'll run the test again. This time, the read will fail (it's still at the end of file), and since read didn't read anything into $line this time the [[ -n "$line" ]] test will also fail, so the while condition as a whole fails and the loop terminates.

EDIT2: The [[ ]] is a bash conditional expression -- it's not a regular command, but it can be used in place of one. Its primary purpose is to succeed or fail, based on the condition inside it. In this case, the -n test means succeed if the operand ("$line") is NONempty. There's a list of other test conditions here, as well as in the man page for the test command.

Note that a conditional expression in [[ ... ]] is subtly different from a test command [ ... ] -- see BashFAQ #031 for differences and a list of available tests. And they're both different from an arithmetic expression with (( ... )), and completely different from a subshell with( ... )...

Answer 3

Using grep with while loop:

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

Using grep . instead of grep "" will skip the empty lines.

Note:

1. Using IFS= keeps any line indentation intact.

2. You should almost always use the -r option with read.

Answer 4

I found some code that reads a file including the last line, and works without the [[ ]] command:

http://www.unix.com/shell-programming-and-scripting/161645-read-file-using-while-loop-not-reading-last-line.html

DONE=false
until $DONE; do
    read s || DONE=true
    # you code
done < FILE