replaced http://serverfault.com/ with https://serverfault.com/

edited Apr 13, 2017 at 12:13

1

Just by coincidence I had to use my ATA-ID-to-device-name script (found here: http://serverfault.com/questions/244944/linux-ata-errors-translating-to-a-device-name/426561#426561 https://serverfault.com/questions/244944/linux-ata-errors-translating-to-a-device-name/426561#426561) on a read-only / partition. In case you're curious, it was an Ubuntu recovery console which will let you access your / partition, but will mount it read-only by default. I am glad about that, because otherwise I would probably never have found out that my script behaves strangely on a R/O system due to a specific line, this one:

IFS=: read HostMain HostMid HostSub <<< "$HostFull"

This does not work if there is no write permission. I wouldn't have assumed it would fail, though. But apparently the <<< operator does require to write some temporary file to somewhere.

But is there any way to circumvent the creation of a temporary file, or, is there any way to specify where the file is written to? In the Ubuntu recovery console, there is---oddly enough---write permission on the /run directory, so that would do, if I could somehow "tell" read to write the temp file to somewhere else than usual.

Just by coincidence I had to use my ATA-ID-to-device-name script (found here: http://serverfault.com/questions/244944/linux-ata-errors-translating-to-a-device-name/426561#426561) on a read-only / partition. In case you're curious, it was an Ubuntu recovery console which will let you access your / partition, but will mount it read-only by default. I am glad about that, because otherwise I would probably never have found out that my script behaves strangely on a R/O system due to a specific line, this one:

IFS=: read HostMain HostMid HostSub <<< "$HostFull"

This does not work if there is no write permission. I wouldn't have assumed it would fail, though. But apparently the <<< operator does require to write some temporary file to somewhere.

But is there any way to circumvent the creation of a temporary file, or, is there any way to specify where the file is written to? In the Ubuntu recovery console, there is---oddly enough---write permission on the /run directory, so that would do, if I could somehow "tell" read to write the temp file to somewhere else than usual.

Just by coincidence I had to use my ATA-ID-to-device-name script (found here: https://serverfault.com/questions/244944/linux-ata-errors-translating-to-a-device-name/426561#426561) on a read-only / partition. In case you're curious, it was an Ubuntu recovery console which will let you access your / partition, but will mount it read-only by default. I am glad about that, because otherwise I would probably never have found out that my script behaves strangely on a R/O system due to a specific line, this one:

IFS=: read HostMain HostMid HostSub <<< "$HostFull"

This does not work if there is no write permission. I wouldn't have assumed it would fail, though. But apparently the <<< operator does require to write some temporary file to somewhere.

But is there any way to circumvent the creation of a temporary file, or, is there any way to specify where the file is written to? In the Ubuntu recovery console, there is---oddly enough---write permission on the /run directory, so that would do, if I could somehow "tell" read to write the temp file to somewhere else than usual.

Old question of mine, but somehow the title is silly. We all know now: you *cannot* use here-document on r/o partition, you need to work around it *entirely*. But the old title suggests this question shows you to use here-document on r/o. NO. YOU CAN'T. You can't cast a spell on /tmp to turn to r/w.

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