Bash: What does “masking return values” mean?
shellcheck generated the following warning
SC2155: Declare and assign separately to avoid masking return
values
For this line of code
local key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
What does "masking return values" mean, and how does it pertain to the aforementioned warning?
bash shell-script shellcheck
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shellcheck generated the following warning
SC2155: Declare and assign separately to avoid masking return
values
For this line of code
local key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
What does "masking return values" mean, and how does it pertain to the aforementioned warning?
bash shell-script shellcheck
asked yesterday
InquisitorInquisitor
304
New contributor
Inquisitor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
shellcheck generated the following warning
SC2155: Declare and assign separately to avoid masking return
values
For this line of code
local key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
What does "masking return values" mean, and how does it pertain to the aforementioned warning?
bash shell-script shellcheck
asked yesterday
InquisitorInquisitor
304
New contributor
Inquisitor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
shellcheck generated the following warning
SC2155: Declare and assign separately to avoid masking return
values
For this line of code
local key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
What does "masking return values" mean, and how does it pertain to the aforementioned warning?
bash shell-script shellcheck
bash shell-script shellcheck
asked yesterday
InquisitorInquisitor
304
New contributor
Inquisitor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked yesterday
InquisitorInquisitor
304
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Inquisitor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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edited yesterday
Inquisitor
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asked yesterday
InquisitorInquisitor
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asked yesterday
InquisitorInquisitor
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304
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1 Answer
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When you declare a variable as either local or exported that in itself is a command that will return success or not.
$ var=$(false)
$ echo $?
1
$ export var=$(false)
$ echo $?
0
So if you wanted to act on the return value of your command (echo "$current_line" | mawk '/.+=.+/ {print $1 }'), you would be unable to since it's going to exit with 0 as long as the local declaration succeeds (which is almost always will).
In order to avoid this it suggests declaring separately and then assigning:
local key_value
key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
This is a shellcheck rule I frequently ignore and IMO is safe to ignore as long as you know you aren't trying to act on the return value of that variable declaration.
You can ignore it by adding the following to the top of your script (Below the hashbang of course):
# shellcheck disable=SC2155
answered yesterday
Jesse_bJesse_b
13.5k23371
1
Folks determining whether their code is "trying to act on the return value" should keep in mind that havingset -eor an ERR trap fire is also an action (though I don't recommend their use regardless).
– Charles Duffy
yesterday
add a comment |
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1 Answer
1
active
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votes
1 Answer
1
active
oldest
votes
active
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active
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votes
When you declare a variable as either local or exported that in itself is a command that will return success or not.
$ var=$(false)
$ echo $?
1
$ export var=$(false)
$ echo $?
0
So if you wanted to act on the return value of your command (echo "$current_line" | mawk '/.+=.+/ {print $1 }'), you would be unable to since it's going to exit with 0 as long as the local declaration succeeds (which is almost always will).
In order to avoid this it suggests declaring separately and then assigning:
local key_value
key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
This is a shellcheck rule I frequently ignore and IMO is safe to ignore as long as you know you aren't trying to act on the return value of that variable declaration.
You can ignore it by adding the following to the top of your script (Below the hashbang of course):
# shellcheck disable=SC2155
answered yesterday
Jesse_bJesse_b
13.5k23371
1
Folks determining whether their code is "trying to act on the return value" should keep in mind that havingset -eor an ERR trap fire is also an action (though I don't recommend their use regardless).
– Charles Duffy
yesterday
add a comment |
When you declare a variable as either local or exported that in itself is a command that will return success or not.
$ var=$(false)
$ echo $?
1
$ export var=$(false)
$ echo $?
0
So if you wanted to act on the return value of your command (echo "$current_line" | mawk '/.+=.+/ {print $1 }'), you would be unable to since it's going to exit with 0 as long as the local declaration succeeds (which is almost always will).
In order to avoid this it suggests declaring separately and then assigning:
local key_value
key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
This is a shellcheck rule I frequently ignore and IMO is safe to ignore as long as you know you aren't trying to act on the return value of that variable declaration.
You can ignore it by adding the following to the top of your script (Below the hashbang of course):
# shellcheck disable=SC2155
answered yesterday
Jesse_bJesse_b
13.5k23371
1
Folks determining whether their code is "trying to act on the return value" should keep in mind that havingset -eor an ERR trap fire is also an action (though I don't recommend their use regardless).
– Charles Duffy
yesterday
add a comment |
When you declare a variable as either local or exported that in itself is a command that will return success or not.
$ var=$(false)
$ echo $?
1
$ export var=$(false)
$ echo $?
0
So if you wanted to act on the return value of your command (echo "$current_line" | mawk '/.+=.+/ {print $1 }'), you would be unable to since it's going to exit with 0 as long as the local declaration succeeds (which is almost always will).
In order to avoid this it suggests declaring separately and then assigning:
local key_value
key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
This is a shellcheck rule I frequently ignore and IMO is safe to ignore as long as you know you aren't trying to act on the return value of that variable declaration.
You can ignore it by adding the following to the top of your script (Below the hashbang of course):
# shellcheck disable=SC2155
answered yesterday
Jesse_bJesse_b
13.5k23371
When you declare a variable as either local or exported that in itself is a command that will return success or not.
$ var=$(false)
$ echo $?
1
$ export var=$(false)
$ echo $?
0
So if you wanted to act on the return value of your command (echo "$current_line" | mawk '/.+=.+/ {print $1 }'), you would be unable to since it's going to exit with 0 as long as the local declaration succeeds (which is almost always will).
In order to avoid this it suggests declaring separately and then assigning:
local key_value
key_value=$(echo "$current_line" | mawk '/.+=.+/ {print $1 }')
This is a shellcheck rule I frequently ignore and IMO is safe to ignore as long as you know you aren't trying to act on the return value of that variable declaration.
You can ignore it by adding the following to the top of your script (Below the hashbang of course):
# shellcheck disable=SC2155
answered yesterday
Jesse_bJesse_b
13.5k23371
answered yesterday
Jesse_bJesse_b
13.5k23371
answered yesterday
Jesse_bJesse_b
13.5k23371
answered yesterday
Jesse_bJesse_b
13.5k23371
13.5k23371
1
Folks determining whether their code is "trying to act on the return value" should keep in mind that havingset -eor an ERR trap fire is also an action (though I don't recommend their use regardless).
– Charles Duffy
yesterday
add a comment |
1
Folks determining whether their code is "trying to act on the return value" should keep in mind that havingset -eor an ERR trap fire is also an action (though I don't recommend their use regardless).
– Charles Duffy
yesterday
1
1
Folks determining whether their code is "trying to act on the return value" should keep in mind that having
set -e or an ERR trap fire is also an action (though I don't recommend their use regardless).– Charles Duffy
yesterday
Folks determining whether their code is "trying to act on the return value" should keep in mind that having
set -e or an ERR trap fire is also an action (though I don't recommend their use regardless).– Charles Duffy
yesterday
add a comment |
Inquisitor is a new contributor. Be nice, and check out our Code of Conduct.
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