Shell Programming and Scripting

Say the file is something like:

word1/word2/word3
word4/word5/word6
word7/word8/word9


How would I extract word9?

awk: Set the field separator appropriately, then, use the END pattern to print the last field of the last line using $NF.

sed: Suppress printing with -n, use $ pattern to detect when you've arrived at the final line, delete everything up to and including the last delimiter in the line, and print.

sh/tail: tail and command substitution can store that last line in a shell variable. Then parameter expansion operators can delete the unwanted content in a manner analogous (but not identical) to what you'd do with sed.

tail/cut: If you know how many fields there are in the line, you can use tail to print the final line and then cut to extract the final field.

No doubt there are other variations. What have you tried?

Regards,
Alister

I am using the sh/tail method, this is my code, but there is an error:

Code:

#!/usr/bin/ksh
ftp -n hostx <<EOF>> Report.txt
user user password
ls /tmp/ReportFile.*
 
EOF
$(tail -1 Report.txt) | grep ReportFile.* > lastword
 
cat lastword

it says "-rw-r--r--: not found" By the way, the last line of the txt file is:

Code:

-rw-r--r--   1 root       sys          85970 Jun 26 19:35 /tmp/ReportFile.0626

from the suggestions of alister there are multiple ways to do this, based on your sample data here is the code:

Code:

$ cat test1
word1/word2/word3
word4/word5/word6
word7/word8/word9

Code:

cat test1 | tr -d '\n' | awk -F/ '{print $NF}'

or

Code:

awk -F/  '{print $NR}' test1 | tail -1

Note: Not all awks retain the values of the field variables in the END section:

Code:

$ echo 1 2 | gawk 'END{print $2}'
2
$ echo 1 2 | nawk 'END{print $2}'

$

Code:

$ echo 1 2 | nawk '{s=$2}END{print s}'
2
$

Is that a current/recent version of nawk?

Not that it changes the fact of the matter, but that behavior has always been a part of POSIX. If I am mistaken and it wasn't specified by the very first version of the standard, it was definitely codified by the second (which is at least 15 years old at this time).

I wonder why any modern, maintained implementation would not be compliant (I do realize that the K in AWK is the person behind nawk and that his work on awk and nawk predates the standard). Since awk generally has no way of indicating when the final record has been reached, aside from the END pattern, it's very useful to keep those variables intact. Also, historical scripts written for such an implementation would either not have been using those variables in END or would have been setting their values, so I don't see any backwards-compatibility issue with becoming compliant.

If that is a current nawk, given the timelines involved, this is on par with having to caution someone about using the $(...) form of command substitution with a recently released version of a POSIX-like shell.

Regards,
Alister

It is the behavior nawk and /usr/xpg4/bin/awk on Solaris (also old awk) and of awk/nawk on AIX.
In my opinion this is in compliance with the POSIX standard (which was modeled after nawk), since POSIX only says something about retaining NF in the END section but it is mum about $0 and $1, $2, ..