1

I have some output that looks like the following:

Gathering data for drive 1 ...
Drive name:  id1,sd@n5000cca17096
Drive Model: HUH721010AL4204
Drive Speed: 7200 RPMs
Drive Temp:  41 C

Gathering data for drive 2 ...
Drive name:  id1,sd@n5000cca24156
Drive Model: HUH721010AL4204
Drive Speed: 7200 RPMs
Drive Temp:  41 C

Gathering data for drive 3 ...
Drive name:  id1,sd@n5000cca8749
Drive Model: HUH721010AL4204
failed to get drive stats

Gathering data for drive 4 ...
Drive name:  id1,sd@n5000cca19183
Drive Model: HUH721010AL4204
Drive Speed: 7200 RPMs
Drive Temp:  41 C

Gathering data for drive 5 ...
Drive name:  id1,sd@n5000cca4607
Drive Model: HUSMH8010BSS204
failed to get drive stats

Gathering data for drive 6 ...
Drive name:  id1,sd@n5000cca10152
Drive Model: HUH721010AL4204
Drive Speed: 7200 RPMs
Drive Temp:  41 C

I would like to print the "Drive name" for any drive in which the drive stats cannot be returned (so matching on failed to get drive stats).

I know how to get the previous line with:

awk '$0=="failed to get drive stats" && $2>1 {print f} {f=$0}'

But that doesn't help me.

Desired output:

Drive name:  id1,sd@n5000cca8749
Drive name:  id1,sd@n5000cca4607

Edit:

For some reason when the output is redirected it doesn't appear the same way as it does on the terminal. If I run:

command >out.txt 2>&1

The output file will look like:

failed to get drive stats
failed to get drive stats

Gathering data for drive 1 ...
Drive name:  id1,sd@n5000cca17096
Drive Model: HUH721010AL4204
Drive Speed: 7200 RPMs
Drive Temp:  41 C

Gathering data for drive 2 ...
Drive name:  id1,sd@n5000cca24156
Drive Model: HUH721010AL4204
Drive Speed: 7200 RPMs
Drive Temp:  41 C

....

Both awk answers provided work but I just have other issues I guess

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4
$ awk -F ':' '$1 == "Drive name" { saved = $0 } $0 == "failed to get drive stats" { print saved }' file
Drive name:  id1,sd@n5000cca8749
Drive name:  id1,sd@n5000cca4607

This first sets the input field separator to a :. It then saves the line in the variable saved whenever a line specifying a drive name is found.

If a line says failed to get drive stats, the current value of saved is printed.

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2
  • It's so strange because if I save the command output to a file this works but trying to read it through a pipe and it doesn't. So it has nothing to do with the awk version – jesse_b Jan 16 '20 at 22:59
  • stderr is unbuffered but stdout is buffered - maybe? – NickD Jan 16 '20 at 23:28
0

This is why awk has a "paragraph mode", all you need is:

$ awk -v RS= -F'\n' '/failed to get drive stats/{print $2}' file
Drive name:  id1,sd@n5000cca8749
Drive name:  id1,sd@n5000cca4607
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0

Tried with Below method and it worked fine

awk '{a[++i]=$0}/failed/{for(x=NR-2;x<NR;x++)print a[x]}' filename| sed -n '1~2p'

output

Drive name:  id1,sd@n5000cca8749
Drive name:  id1,sd@n5000cca4607
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1
  • Ask yourself what the difference is between i and NR. Now ask yourself why you need i. Now ask yourself why you're printing 2 lines at a time with a loop in awk and then deleting the 2nd line of every pair with sed. You also never need sed when you're using awk anyway. – Ed Morton Jan 18 '20 at 2:02

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