-1

I am trying to automate the use of shred and putting the output into log files. Currently I am copying the serial number manually using 

hdparm -I /dev/sd? | grep 'Serial\ Number'

I know that there is a way to have grep give me only the number and not the "Serial Number" text before it but I don't know how. Could someone how knows reg expressions help me?

Gilles 'SO- stop being evil'
  • 807,993
  • 194
  • 1,674
  • 2,175
Ben Stumpf
  • 7
  • 1

4 Answers4

5

Try awk instead of grep:

hdparm -I /dev/sd? | awk '/Serial Number/ { print $3 }'

or specify separator rather than accepting default of whitespace

hdparm -I /dev/sd? | awk -F':' '/Serial Number/ { print $2 }'
Stephen Kitt
  • 411,918
  • 54
  • 1,065
  • 1,164
user4556274
  • 8,725
  • 2
  • 31
  • 37
3

As that xkcd strip mentions perl, let's have a perl solution:

hdparm -I /dev/sd? | perl -nle '/Serial Number:\s+(.+)$/ && print $1'

A perl version of the awk solution in the other answer:

hdparm -I /dev/sd? | perl -anle '/Serial Number:/ && print $F[2]'
Henrik supports the community
  • 5,181
  • 2
  • 14
  • 31
3

Try

hdparm -I /dev/sd? | grep -oP 'Serial Number:\s*\K.*'

This uses positive lookbehind to ignore pattern before our required string.. in this case Serial Number:\s*

Community
  • 1
Sundeep
  • 11,753
  • 2
  • 26
  • 57
1

sed?

hdparm -I /dev/sd? | sed -n 's/^.*Serial\ Number:  *\(.*\)$/\1/p'

(probably lots of other ways to do this using sed - this is just one way that I like: suppress the default print; match the required portion of the line; replace the entire line with it; then print it out.)

pd9370
  • 11
  • 2