bash string increase from vda to vdb in a loop
I would like to increase a string by one, for example, from vda to vdb, from vdb to vdc and so on.
I was able to do it in one of the languages in the past by doing something like:
$c="vdb"+1
and
c == vdc
after that.
currently, I have a line which gets the last vd* disk from a VM:
current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)
I want it to be added to virsh disk-attach command automatically as a target option, like this one:
virsh disk-attach $VM $DISK_FILE $DISK_NAME
SO I could do $DISK_NAME from $current automatically, without predefined case or smth...
bash string
edited Dec 12 at 16:22
SouravGhosh
409310
asked Dec 12 at 10:05
BiG_NoBoDy
288
add a comment |
I would like to increase a string by one, for example, from vda to vdb, from vdb to vdc and so on.
I was able to do it in one of the languages in the past by doing something like:
$c="vdb"+1
and
c == vdc
after that.
currently, I have a line which gets the last vd* disk from a VM:
current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)
I want it to be added to virsh disk-attach command automatically as a target option, like this one:
virsh disk-attach $VM $DISK_FILE $DISK_NAME
SO I could do $DISK_NAME from $current automatically, without predefined case or smth...
bash string
edited Dec 12 at 16:22
SouravGhosh
409310
asked Dec 12 at 10:05
BiG_NoBoDy
288
add a comment |
I would like to increase a string by one, for example, from vda to vdb, from vdb to vdc and so on.
I was able to do it in one of the languages in the past by doing something like:
$c="vdb"+1
and
c == vdc
after that.
currently, I have a line which gets the last vd* disk from a VM:
current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)
I want it to be added to virsh disk-attach command automatically as a target option, like this one:
virsh disk-attach $VM $DISK_FILE $DISK_NAME
SO I could do $DISK_NAME from $current automatically, without predefined case or smth...
bash string
edited Dec 12 at 16:22
SouravGhosh
409310
asked Dec 12 at 10:05
BiG_NoBoDy
288
I would like to increase a string by one, for example, from vda to vdb, from vdb to vdc and so on.
I was able to do it in one of the languages in the past by doing something like:
$c="vdb"+1
and
c == vdc
after that.
currently, I have a line which gets the last vd* disk from a VM:
current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)
I want it to be added to virsh disk-attach command automatically as a target option, like this one:
virsh disk-attach $VM $DISK_FILE $DISK_NAME
SO I could do $DISK_NAME from $current automatically, without predefined case or smth...
bash string
bash string
edited Dec 12 at 16:22
SouravGhosh
409310
asked Dec 12 at 10:05
BiG_NoBoDy
288
edited Dec 12 at 16:22
SouravGhosh
409310
asked Dec 12 at 10:05
BiG_NoBoDy
288
edited Dec 12 at 16:22
SouravGhosh
409310
edited Dec 12 at 16:22
SouravGhosh
409310
edited Dec 12 at 16:22
SouravGhosh
409310
409310
asked Dec 12 at 10:05
BiG_NoBoDy
288
asked Dec 12 at 10:05
BiG_NoBoDy
288
asked Dec 12 at 10:05
BiG_NoBoDy
288
288
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
letter=${current#??}
letter=$( tr 'a-y' 'b-z' <<<"$letter" )
next="${current%?}$letter"
This first extracts the last letter of $current by deleting the first two characters. It then uses tr to shift the letter to the next one in the alphabet.
At the end, next is assigned the first two characters of $current (the last one removed) and concatenates that with the shifted letter.
If $current is vdc, $next will be vdd.
answered Dec 12 at 10:09
Kusalananda
121k16228372
I understand, but it will stop at when hits the last one... I do not know what the last will be:current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)so I want to add to this a "next" disk
– BiG_NoBoDy
Dec 12 at 10:11
@BiG_NoBoDy See update. You question does not show that you know how manyvdstrings that you want to create, or what these string are, or any other background or context.
– Kusalananda
Dec 12 at 10:13
Ok, I'll update it in propper way.
– BiG_NoBoDy
Dec 12 at 10:14
@BiG_NoBoDy Thanks! See updated answer.
– Kusalananda
Dec 12 at 10:34
Kusalananda > thank you
– BiG_NoBoDy
Dec 12 at 15:16
add a comment |
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1 Answer
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oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
letter=${current#??}
letter=$( tr 'a-y' 'b-z' <<<"$letter" )
next="${current%?}$letter"
This first extracts the last letter of $current by deleting the first two characters. It then uses tr to shift the letter to the next one in the alphabet.
At the end, next is assigned the first two characters of $current (the last one removed) and concatenates that with the shifted letter.
If $current is vdc, $next will be vdd.
answered Dec 12 at 10:09
Kusalananda
121k16228372
I understand, but it will stop at when hits the last one... I do not know what the last will be:current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)so I want to add to this a "next" disk
– BiG_NoBoDy
Dec 12 at 10:11
@BiG_NoBoDy See update. You question does not show that you know how manyvdstrings that you want to create, or what these string are, or any other background or context.
– Kusalananda
Dec 12 at 10:13
Ok, I'll update it in propper way.
– BiG_NoBoDy
Dec 12 at 10:14
@BiG_NoBoDy Thanks! See updated answer.
– Kusalananda
Dec 12 at 10:34
Kusalananda > thank you
– BiG_NoBoDy
Dec 12 at 15:16
add a comment |
letter=${current#??}
letter=$( tr 'a-y' 'b-z' <<<"$letter" )
next="${current%?}$letter"
This first extracts the last letter of $current by deleting the first two characters. It then uses tr to shift the letter to the next one in the alphabet.
At the end, next is assigned the first two characters of $current (the last one removed) and concatenates that with the shifted letter.
If $current is vdc, $next will be vdd.
answered Dec 12 at 10:09
Kusalananda
121k16228372
I understand, but it will stop at when hits the last one... I do not know what the last will be:current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)so I want to add to this a "next" disk
– BiG_NoBoDy
Dec 12 at 10:11
@BiG_NoBoDy See update. You question does not show that you know how manyvdstrings that you want to create, or what these string are, or any other background or context.
– Kusalananda
Dec 12 at 10:13
Ok, I'll update it in propper way.
– BiG_NoBoDy
Dec 12 at 10:14
@BiG_NoBoDy Thanks! See updated answer.
– Kusalananda
Dec 12 at 10:34
Kusalananda > thank you
– BiG_NoBoDy
Dec 12 at 15:16
add a comment |
letter=${current#??}
letter=$( tr 'a-y' 'b-z' <<<"$letter" )
next="${current%?}$letter"
This first extracts the last letter of $current by deleting the first two characters. It then uses tr to shift the letter to the next one in the alphabet.
At the end, next is assigned the first two characters of $current (the last one removed) and concatenates that with the shifted letter.
If $current is vdc, $next will be vdd.
answered Dec 12 at 10:09
Kusalananda
121k16228372
letter=${current#??}
letter=$( tr 'a-y' 'b-z' <<<"$letter" )
next="${current%?}$letter"
This first extracts the last letter of $current by deleting the first two characters. It then uses tr to shift the letter to the next one in the alphabet.
At the end, next is assigned the first two characters of $current (the last one removed) and concatenates that with the shifted letter.
If $current is vdc, $next will be vdd.
answered Dec 12 at 10:09
Kusalananda
121k16228372
edited Dec 12 at 10:33
answered Dec 12 at 10:09
Kusalananda
121k16228372
answered Dec 12 at 10:09
Kusalananda
121k16228372
answered Dec 12 at 10:09
Kusalananda
121k16228372
121k16228372
I understand, but it will stop at when hits the last one... I do not know what the last will be:current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)so I want to add to this a "next" disk
– BiG_NoBoDy
Dec 12 at 10:11
@BiG_NoBoDy See update. You question does not show that you know how manyvdstrings that you want to create, or what these string are, or any other background or context.
– Kusalananda
Dec 12 at 10:13
Ok, I'll update it in propper way.
– BiG_NoBoDy
Dec 12 at 10:14
@BiG_NoBoDy Thanks! See updated answer.
– Kusalananda
Dec 12 at 10:34
Kusalananda > thank you
– BiG_NoBoDy
Dec 12 at 15:16
add a comment |
I understand, but it will stop at when hits the last one... I do not know what the last will be:current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1)so I want to add to this a "next" disk
– BiG_NoBoDy
Dec 12 at 10:11
@BiG_NoBoDy See update. You question does not show that you know how manyvdstrings that you want to create, or what these string are, or any other background or context.
– Kusalananda
Dec 12 at 10:13
Ok, I'll update it in propper way.
– BiG_NoBoDy
Dec 12 at 10:14
@BiG_NoBoDy Thanks! See updated answer.
– Kusalananda
Dec 12 at 10:34
Kusalananda > thank you
– BiG_NoBoDy
Dec 12 at 15:16
I understand, but it will stop at when hits the last one... I do not know what the last will be:
current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1) so I want to add to this a "next" disk– BiG_NoBoDy
Dec 12 at 10:11
I understand, but it will stop at when hits the last one... I do not know what the last will be:
current=$(virsh domblklist cic-1_vm | grep vd | awk '{print $1}' | sort -n | tail -n 1) so I want to add to this a "next" disk– BiG_NoBoDy
Dec 12 at 10:11
@BiG_NoBoDy See update. You question does not show that you know how many
vd strings that you want to create, or what these string are, or any other background or context.– Kusalananda
Dec 12 at 10:13
@BiG_NoBoDy See update. You question does not show that you know how many
vd strings that you want to create, or what these string are, or any other background or context.– Kusalananda
Dec 12 at 10:13
Ok, I'll update it in propper way.
– BiG_NoBoDy
Dec 12 at 10:14
Ok, I'll update it in propper way.
– BiG_NoBoDy
Dec 12 at 10:14
@BiG_NoBoDy Thanks! See updated answer.
– Kusalananda
Dec 12 at 10:34
@BiG_NoBoDy Thanks! See updated answer.
– Kusalananda
Dec 12 at 10:34
Kusalananda > thank you
– BiG_NoBoDy
Dec 12 at 15:16
Kusalananda > thank you
– BiG_NoBoDy
Dec 12 at 15:16
add a comment |
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