Re: [CentOS] Need fstab-decode for CentOS 8
Am 28.02.22 um 05:45 schrieb Robert Nichols:
On 2/27/22 12:26 PM, cen...@niob.at wrote:
Am 27.02.22 um 04:33 schrieb Robert Nichols:
Does anything for CentOS 8 provide the function of the fstab-decode
utility?
Entries in /proc/mounts and /etc/fstab can have escape sequences for
certain special characters, and I need to decode that.
Preface: Never heard of fstab-decode before. Researching the command
made me really wonder why it was invented. Especially since I have
never seen an /etc/fstab with "escape sequences" or "special
characters" since at least 1990 (If I am wrong: Please show me such a
fstab file).
So why not just use:
umount $(awk '$3 == "vfat" {print $2}' /etc/fstab)
instead of the seemingly canonical use of fstab-decode
fstab-decode umount $(awk '$3 == "vfat" { print $2 }' /etc/fstab)
Those samples break if the mount point directory name contains spaces,
tabs, or whatever other characters I don't know about that also get
represented by escape sequences. I'm not actually using it with
/etc/fstab, but with /proc/mounts which uses the same convention. I
can control /etc/fstab and avoid the problem, but I cannot control how
some auto-mounted foreign filesystem might be named. I have a script
that needs to be robust in the face of such names.
Get creative! Unix administration is a creative job. Having said this:
Using white space within mount points is asking for trouble anyway. If
you really want this in the most generic way, then do the unquoting with
something like this:
awk '$3 == "vfat" {print $2}' /etc/fstab | perl -pl000 -e
's/\\([0-7]{3})/chr(oct($1))/eg' | xargs -0 -n 1 -r umount
This seems to be the unixy way to do this.
If you really need the fstab-decode program put this in a script (if you
want to be able to use commands with arguments you may choose to remove
the double quotes in the argument to xargs):
#!/bin/bash
# a simple fstab-decode implementation
CMD="$1"
shift
while [ -n "$1" ] ; do
echo -E "$1"
shift
done | perl -pl000 -e 's/\\([0-7]{3})/chr(oct($1))/eg;' | xargs -0 -n 1 -r
"$CMD"
Peter
___
CentOS mailing list
CentOS@centos.org
https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Need fstab-decode for CentOS 8
On 2/27/22 12:26 PM, cen...@niob.at wrote:
Am 27.02.22 um 04:33 schrieb Robert Nichols:
Does anything for CentOS 8 provide the function of the fstab-decode utility?
Entries in /proc/mounts and /etc/fstab can have escape sequences for certain special characters, and I need to decode that.
Preface: Never heard of fstab-decode before. Researching the command made me really wonder why it
was invented. Especially since I have never seen an /etc/fstab with "escape sequences" or
"special characters" since at least 1990 (If I am wrong: Please show me such a fstab
file).
So why not just use:
umount $(awk '$3 == "vfat" {print $2}' /etc/fstab)
instead of the seemingly canonical use of fstab-decode
fstab-decode umount $(awk '$3 == "vfat" { print $2 }' /etc/fstab)
Those samples break if the mount point directory name contains spaces, tabs, or
whatever other characters I don't know about that also get represented by
escape sequences. I'm not actually using it with /etc/fstab, but with
/proc/mounts which uses the same convention. I can control /etc/fstab and avoid
the problem, but I cannot control how some auto-mounted foreign filesystem
might be named. I have a script that needs to be robust in the face of such
names.
--
Bob Nichols "NOSPAM" is really part of my email address.
Do NOT delete it.
___
CentOS mailing list
CentOS@centos.org
https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Need fstab-decode for CentOS 8
Am 27.02.22 um 04:33 schrieb Robert Nichols:
Does anything for CentOS 8 provide the function of the fstab-decode
utility?
Entries in /proc/mounts and /etc/fstab can have escape sequences for
certain special characters, and I need to decode that.
Preface: Never heard of fstab-decode before. Researching the command
made me really wonder why it was invented. Especially since I have never
seen an /etc/fstab with "escape sequences" or "special characters" since
at least 1990 (If I am wrong: Please show me such a fstab file).
So why not just use:
umount $(awk '$3 == "vfat" {print $2}' /etc/fstab)
instead of the seemingly canonical use of fstab-decode
fstab-decode umount $(awk '$3 == "vfat" { print $2 }' /etc/fstab)
Myself, I would use the super-standard xargs, that can even take care of
the case that there might be no matching lines, that is:
awk '$3 == "vfat" {print $2}' /etc/fstab | xargs -r umount
And if there REALLY are files around with "special characters" I would
do it like this:
awk '$3 == "vfat" {ORS="\0" ; print $2}' /etc/fstab | xargs -0 -r
umount
I consider this a standard idiom usable for many more use cases than
just parsing /etc/fstab
Peter
___
CentOS mailing list
CentOS@centos.org
https://lists.centos.org/mailman/listinfo/centos
