问题
I am working on a shell script with exiftool to automatically change some exif tags on pictures contained in a certain folder and I would like to use the output to get a notification on my NAS (a QNAP) when the job is completed.
Everything works already, but - as the notification system truncates the message - I would like to receive just the information I need, i.e. the last line of the shell output, which is for example the following:
Warning: [minor] Entries in IFD0 were out of sequence. Fixed. - 2015-07-12 15.41.06.jpg
4512 files failed condition
177 image files updated
The problem is that currently I only receive the following notification:
Exiftool cronjob completed on Camera: 4512 files failed condition
What I would like to get instead is:
Exiftool cronjob completed on Camera: 177 image files updated
The script is the following:
#!/bin/sh
# exiftool script for 2002 problem
dir="/share/Multimedia/Camera"
cd "$dir"
FOLDER="$(printf '%s\n' "${PWD##*/}")"
OUTPUT="$(exiftool -overwrite_original -r '-CreateDate<DateTimeOriginal' -if '$CreateDate eq "2002:12:08 12:00:00"' -if '$DateTimeOriginal ne $CreateDate' *.[Jj][Pp][Gg])"
/sbin/notice_log_tool -a "Exiftool cronjob completed on ${FOLDER}: ${OUTPUT}" --severity=5
exit 0
To do that I played with the $OUTPUT variable using | tail -1, but probably I make some basic errors and I receive something like:
Exiftool cronjob completed on Camera: 4512 files failed condition | tail -1
How to do it in the right way? Thanks
回答1:
Put the tail inside the capturing parens.
OUTPUT=$(exif ... | tail -1)
You don't need the double quotes here. I'm guessing that you tried
OUTPUT="$(exif ...) | tail -1"
回答2:
Probably an old post to be answering now, but try using the -n flag (see tail --help) and wrap the command output using ticks.
OUTPUT=`exif ... | tail -n 1`
(user464502's answer did not work for me as the tail command does not recognize the parameter "-1")
来源：https://stackoverflow.com/questions/31381373/get-last-line-of-shell-output-as-a-variable