CODEWITHSUNDEEP
linuxshellawkcat
Argus
Argus

Reputation: 53

Add timestamp to cat output from shell script

I have a small script that cats the output from the ttyUSB to a file I would like to prepend a timestamp to each line. From the command line this does everything I want:

$ cat /dev/ttyUSB0 /home/pi/daily_logs/ttyUSSB0 | awk '{ print strftime("%Y-%m-%d %H:%M:%S"), $0; }

My issue is that when I add it to a script everything works but the awk timestamp isn't added. My script line looks like this:

cat < /dev/ttyUSB0 > /home/pi/daily_logs/ttyUSB0 | awk '{ print strftime("%Y-%m-%d %H:%M:%S"), $0; } &

Any help getting this going would be appreciated.

Upvotes: 5

Views: 7072

Answers (3)

Kevin Beck
Kevin Beck

Reputation: 2390

You need to put the > /home/pi/daily_logs/ttyUSB0 after the pipe. Like so:

cat < /dev/ttyUSB0 | awk '{ print strftime("%Y-%m-%d %H:%M:%S"), $0; }' > /home/pi/daily_logs/ttyUSB0

Upvotes: 1

William Pursell
William Pursell

Reputation: 212238

Useless use of cat is impeding the solution. To minimize the changes needed, you can also do:

< /dev/ttyUSB0 > /home/pi/daily_logs/ttyUSB0 awk '...' &

Upvotes: 0

PleaseStand
PleaseStand

Reputation: 32072

You need to redirect awk's output to the file, not cat's. The way you have it, awk gets nothing. Actually, you may not need cat at all:

awk '{ print strftime("%Y-%m-%d %H:%M:%S"), $0; }' /dev/ttyUSB0 > /home/pi/daily_logs/ttyUSB0 &

Upvotes: 8

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