Parse output of a command in terminal

Question

I am running a heroku command heroku pg:backups:capture --app appname to backup a database, which returns an output in the terminal like this:

Use Ctrl-C at any time to stop monitoring progress; the backup will continue running.
Use heroku pg:backups:info to check progress.
Stop a running backup with heroku pg:backups:cancel.

Starting backup of postgresql-xxxxxxxxxx... done
Backing up DATABASE to b007... done

How can I store the backup name b007 to a variable automatically?

SLePort · Accepted Answer · 2019-11-13 21:42:16Z

3

You could pipe your command to sed to extract the desired string:

 dbname=$(heroku pg:backups:capture --app appname | sed -n 's/.*DATABASE to \([^\.]*\)\.\.\..*/\1/p')

answered Nov 13, 2019 at 21:42

SLePort

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2 Comments

vikiboy Over a year ago

Actually this doesn't work. After running the heroku command, the terminal interface shows the progress, which looks something like this ibb.co/ZVQvW0W, and after the backup is complete, it shows as done. Maybe that's why the command you suggested doesn't work?

builder-7000 Over a year ago

@vikiboy try adding 2>&1 before the pipe. It could be that heroku uses stderr instead of stdout.

joelac · Accepted Answer · 2019-11-13 22:00:36Z

2

You could redirect via pipe | the output of the program to

grep "Backing up DATABASE to " | awk '{print substr($5,0,5)}'

It would be:

var=$(heroku pg:backups:capture --app appname | grep "Backing up DATABASE to " | awk '{print substr($5,0,5)}')

edited Nov 13, 2019 at 22:00

answered Nov 13, 2019 at 21:51

joelac

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2 Comments

vikiboy Over a year ago

I edited the output line in the question. Will that update your answer? Sorry for the trouble. I am seeing time and check as the output with your suggestion.

joelac Over a year ago

Depending on the output you just have to change the parameter you give to grep and awk. grep will filter all the lines that do not contain the string you provide, and awk will take out the part you want from the line.

Paul Hodges · Accepted Answer · 2019-11-13 22:05:00Z

0

Simplistic possibility:

while read -r line
do echo "$line"
   case "$line" in
   Backing\ up\ DATABASE\ to\ *done)
       backup="${line%%... done}"
       backup="${backup##* }"
   esac
done < <( heroku pg:backups:capture --app appname )
echo "Backup: [$backup]"

answered Nov 13, 2019 at 22:05

Paul Hodges

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2 Comments

vikiboy Over a year ago

Backup: [] Tried it. I am getting this.

Paul Hodges Over a year ago

Make sure the match string is accurate. This worked for what I copy/pasted from your OP, but if the output differs you'll have to tweak.

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