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}
I have a script where I want to list USB devices using the command lsblk.
The command:
$ lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb
which results in
sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2
I want to save the result in a variable to work later, so I write
$ usbs=$(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
What I was expecting is that the variable usbs stores the result in two whole lines like above. But if I run:
for i in ${usbs[@]}; do
echo $i
done
I get the result split into words:
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
Question:
Is there a way in which, using the grep command, I can store the result of the command as two whole lines?
I prefer to know if there's a simple solution instead of dumping the result in a file and then read it.
bash grep usb variable lsblk
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I have a script where I want to list USB devices using the command lsblk.
The command:
$ lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb
which results in
sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2
I want to save the result in a variable to work later, so I write
$ usbs=$(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
What I was expecting is that the variable usbs stores the result in two whole lines like above. But if I run:
for i in ${usbs[@]}; do
echo $i
done
I get the result split into words:
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
Question:
Is there a way in which, using the grep command, I can store the result of the command as two whole lines?
I prefer to know if there's a simple solution instead of dumping the result in a file and then read it.
bash grep usb variable lsblk
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
Tryecho "${#usbs[@]}"to see the number of items in theusbs"array", or"${!usbs[@]}"to list its indices. Or print it withecho "$usbs". It is likely storing what you are expecting it to.
– fra-san
5 hours ago
1
Double-quote your variables (and$(...)constructs) when you reference them and the shell will keep your whitespace intact. But be aware the shell won't automatically assign array elements based on newlines. It will still be one string, just with a newline in the middle.
– roaima
5 hours ago
@Christopher I like your solution but gave me a headache :), because subsecuents comands use the IFS set before... it took me some time to figure what was happening, it does it silently.
– guillermo chamorro
3 hours ago
var=$(...)is equivalent tovar="$(...)"
– Jesse_b
2 hours ago
add a comment |
I have a script where I want to list USB devices using the command lsblk.
The command:
$ lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb
which results in
sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2
I want to save the result in a variable to work later, so I write
$ usbs=$(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
What I was expecting is that the variable usbs stores the result in two whole lines like above. But if I run:
for i in ${usbs[@]}; do
echo $i
done
I get the result split into words:
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
Question:
Is there a way in which, using the grep command, I can store the result of the command as two whole lines?
I prefer to know if there's a simple solution instead of dumping the result in a file and then read it.
bash grep usb variable lsblk
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I have a script where I want to list USB devices using the command lsblk.
The command:
$ lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb
which results in
sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2
I want to save the result in a variable to work later, so I write
$ usbs=$(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
What I was expecting is that the variable usbs stores the result in two whole lines like above. But if I run:
for i in ${usbs[@]}; do
echo $i
done
I get the result split into words:
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
Question:
Is there a way in which, using the grep command, I can store the result of the command as two whole lines?
I prefer to know if there's a simple solution instead of dumping the result in a file and then read it.
bash grep usb variable lsblk
bash grep usb variable lsblk
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
edited 26 mins ago
Jeff Schaller♦
45.8k1165149
45.8k1165149
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
asked 5 hours ago
guillermo chamorroguillermo chamorro
1143
1143
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
guillermo chamorro is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
Tryecho "${#usbs[@]}"to see the number of items in theusbs"array", or"${!usbs[@]}"to list its indices. Or print it withecho "$usbs". It is likely storing what you are expecting it to.
– fra-san
5 hours ago
1
Double-quote your variables (and$(...)constructs) when you reference them and the shell will keep your whitespace intact. But be aware the shell won't automatically assign array elements based on newlines. It will still be one string, just with a newline in the middle.
– roaima
5 hours ago
@Christopher I like your solution but gave me a headache :), because subsecuents comands use the IFS set before... it took me some time to figure what was happening, it does it silently.
– guillermo chamorro
3 hours ago
var=$(...)is equivalent tovar="$(...)"
– Jesse_b
2 hours ago
add a comment |
1
Tryecho "${#usbs[@]}"to see the number of items in theusbs"array", or"${!usbs[@]}"to list its indices. Or print it withecho "$usbs". It is likely storing what you are expecting it to.
– fra-san
5 hours ago
1
Double-quote your variables (and$(...)constructs) when you reference them and the shell will keep your whitespace intact. But be aware the shell won't automatically assign array elements based on newlines. It will still be one string, just with a newline in the middle.
– roaima
5 hours ago
@Christopher I like your solution but gave me a headache :), because subsecuents comands use the IFS set before... it took me some time to figure what was happening, it does it silently.
– guillermo chamorro
3 hours ago
var=$(...)is equivalent tovar="$(...)"
– Jesse_b
2 hours ago
1
1
Try
echo "${#usbs[@]}" to see the number of items in the usbs "array", or "${!usbs[@]}" to list its indices. Or print it with echo "$usbs". It is likely storing what you are expecting it to.– fra-san
5 hours ago
Try
echo "${#usbs[@]}" to see the number of items in the usbs "array", or "${!usbs[@]}" to list its indices. Or print it with echo "$usbs". It is likely storing what you are expecting it to.– fra-san
5 hours ago
1
1
Double-quote your variables (and
$(...) constructs) when you reference them and the shell will keep your whitespace intact. But be aware the shell won't automatically assign array elements based on newlines. It will still be one string, just with a newline in the middle.– roaima
5 hours ago
Double-quote your variables (and
$(...) constructs) when you reference them and the shell will keep your whitespace intact. But be aware the shell won't automatically assign array elements based on newlines. It will still be one string, just with a newline in the middle.– roaima
5 hours ago
@Christopher I like your solution but gave me a headache :), because subsecuents comands use the IFS set before... it took me some time to figure what was happening, it does it silently.
– guillermo chamorro
3 hours ago
@Christopher I like your solution but gave me a headache :), because subsecuents comands use the IFS set before... it took me some time to figure what was happening, it does it silently.
– guillermo chamorro
3 hours ago
var=$(...) is equivalent to var="$(...)"– Jesse_b
2 hours ago
var=$(...) is equivalent to var="$(...)"– Jesse_b
2 hours ago
add a comment |
1 Answer
1
active
oldest
votes
This is a good situation to use readarray/mapfile:
readarray -t usbs < <(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
This will create an array with your output where each line is separated into it's own element.
In your case it would make an array like:
usbs=(
'sdb usb Kingston DataTraveler 2.0'
'sdc usb Kingston DT 101 G2'
)
As is you are assigning your entire output to a single variable (not an array) which essentially does this:
usbs='sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2 '
In order to make it an array you would do:
usbs=($(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb))
but this would make each word separated by whitespace into its own element, equivalent to:
usbs=(
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
)
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
This is a good situation to use readarray/mapfile:
readarray -t usbs < <(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
This will create an array with your output where each line is separated into it's own element.
In your case it would make an array like:
usbs=(
'sdb usb Kingston DataTraveler 2.0'
'sdc usb Kingston DT 101 G2'
)
As is you are assigning your entire output to a single variable (not an array) which essentially does this:
usbs='sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2 '
In order to make it an array you would do:
usbs=($(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb))
but this would make each word separated by whitespace into its own element, equivalent to:
usbs=(
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
)
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
add a comment |
This is a good situation to use readarray/mapfile:
readarray -t usbs < <(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
This will create an array with your output where each line is separated into it's own element.
In your case it would make an array like:
usbs=(
'sdb usb Kingston DataTraveler 2.0'
'sdc usb Kingston DT 101 G2'
)
As is you are assigning your entire output to a single variable (not an array) which essentially does this:
usbs='sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2 '
In order to make it an array you would do:
usbs=($(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb))
but this would make each word separated by whitespace into its own element, equivalent to:
usbs=(
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
)
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
add a comment |
This is a good situation to use readarray/mapfile:
readarray -t usbs < <(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
This will create an array with your output where each line is separated into it's own element.
In your case it would make an array like:
usbs=(
'sdb usb Kingston DataTraveler 2.0'
'sdc usb Kingston DT 101 G2'
)
As is you are assigning your entire output to a single variable (not an array) which essentially does this:
usbs='sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2 '
In order to make it an array you would do:
usbs=($(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb))
but this would make each word separated by whitespace into its own element, equivalent to:
usbs=(
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
)
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
This is a good situation to use readarray/mapfile:
readarray -t usbs < <(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb)
This will create an array with your output where each line is separated into it's own element.
In your case it would make an array like:
usbs=(
'sdb usb Kingston DataTraveler 2.0'
'sdc usb Kingston DT 101 G2'
)
As is you are assigning your entire output to a single variable (not an array) which essentially does this:
usbs='sdb usb Kingston DataTraveler 2.0
sdc usb Kingston DT 101 G2 '
In order to make it an array you would do:
usbs=($(lsblk -o NAME,TRAN,VENDOR,MODEL | grep usb))
but this would make each word separated by whitespace into its own element, equivalent to:
usbs=(
sdb
usb
Kingston
DataTraveler
2.0
sdc
usb
Kingston
DT
101
G2
)
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
answered 5 hours ago
Jesse_bJesse_b
15.3k33574
15.3k33574
add a comment |
add a comment |
guillermo chamorro is a new contributor. Be nice, and check out our Code of Conduct.
guillermo chamorro is a new contributor. Be nice, and check out our Code of Conduct.
guillermo chamorro is a new contributor. Be nice, and check out our Code of Conduct.
guillermo chamorro is a new contributor. Be nice, and check out our Code of Conduct.
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1
Try
echo "${#usbs[@]}"to see the number of items in theusbs"array", or"${!usbs[@]}"to list its indices. Or print it withecho "$usbs". It is likely storing what you are expecting it to.– fra-san
5 hours ago
1
Double-quote your variables (and
$(...)constructs) when you reference them and the shell will keep your whitespace intact. But be aware the shell won't automatically assign array elements based on newlines. It will still be one string, just with a newline in the middle.– roaima
5 hours ago
@Christopher I like your solution but gave me a headache :), because subsecuents comands use the IFS set before... it took me some time to figure what was happening, it does it silently.
– guillermo chamorro
3 hours ago
var=$(...)is equivalent tovar="$(...)"– Jesse_b
2 hours ago