What does the slash do in 'case $1/$2' in shell script (/bin/sh)
Found this example on the arch wiki
#!/bin/sh
case $1/$2 in
pre/*)
echo "Going to $2..."
;;
post/*)
echo "Waking up from $2..."
;;
esac
and can't make out if it's a logical operator or something else.
shell scripting slash
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
add a comment |
Found this example on the arch wiki
#!/bin/sh
case $1/$2 in
pre/*)
echo "Going to $2..."
;;
post/*)
echo "Waking up from $2..."
;;
esac
and can't make out if it's a logical operator or something else.
shell scripting slash
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
it matches the/inpre/*andpost/*
– ctrl-alt-delor
Dec 22 '18 at 17:46
It is a trick to test $1 and $2 at the same time.
– Thorbjørn Ravn Andersen
Dec 23 '18 at 1:04
add a comment |
Found this example on the arch wiki
#!/bin/sh
case $1/$2 in
pre/*)
echo "Going to $2..."
;;
post/*)
echo "Waking up from $2..."
;;
esac
and can't make out if it's a logical operator or something else.
shell scripting slash
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
Found this example on the arch wiki
#!/bin/sh
case $1/$2 in
pre/*)
echo "Going to $2..."
;;
post/*)
echo "Waking up from $2..."
;;
esac
and can't make out if it's a logical operator or something else.
shell scripting slash
shell scripting slash
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
edited Dec 22 '18 at 17:45
ctrl-alt-delor
11.8k42260
11.8k42260
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
asked Dec 22 '18 at 16:22
James LanghamJames Langham
182
182
it matches the/inpre/*andpost/*
– ctrl-alt-delor
Dec 22 '18 at 17:46
It is a trick to test $1 and $2 at the same time.
– Thorbjørn Ravn Andersen
Dec 23 '18 at 1:04
add a comment |
it matches the/inpre/*andpost/*
– ctrl-alt-delor
Dec 22 '18 at 17:46
It is a trick to test $1 and $2 at the same time.
– Thorbjørn Ravn Andersen
Dec 23 '18 at 1:04
it matches the
/ in pre/* and post/*– ctrl-alt-delor
Dec 22 '18 at 17:46
it matches the
/ in pre/* and post/*– ctrl-alt-delor
Dec 22 '18 at 17:46
It is a trick to test $1 and $2 at the same time.
– Thorbjørn Ravn Andersen
Dec 23 '18 at 1:04
It is a trick to test $1 and $2 at the same time.
– Thorbjørn Ravn Andersen
Dec 23 '18 at 1:04
add a comment |
1 Answer
1
active
oldest
votes
There is nothing special here. The syntax for case is
case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
In the example in the question, word is built by combining $1, / and $2. / doesn't have a special meaning at all, it's just a character.
PS: Practically the usage is a bit strange, as the $2 part afterwards gets matched against * so the value of $2 doesn't really matter. One could, in the context described in the Wiki, also write
#!/bin/sh
case $1 in
pre)
echo "Going to $2..."
;;
post)
echo "Waking up from $2..."
;;
esac
But there might be cases where suspend, hibernate or hybrid (the possible values for $2) are relevant, so it's just a general pattern here.
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
3
maybe$1ispre/heatand$2isovenin which case your code would not match, but the original would ;-)
– mosvy
Dec 22 '18 at 17:19
1
@mosvy True. But in the context of the script as explained on the Arch Wiki page linked in the question that's something which "should not happen". Haha.
– nohillside
Dec 22 '18 at 17:23
They would not be equivalent in cases where$1ispre/something.
– Stéphane Chazelas
Dec 22 '18 at 17:58
add a comment |
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1 Answer
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active
oldest
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1 Answer
1
active
oldest
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oldest
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oldest
votes
There is nothing special here. The syntax for case is
case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
In the example in the question, word is built by combining $1, / and $2. / doesn't have a special meaning at all, it's just a character.
PS: Practically the usage is a bit strange, as the $2 part afterwards gets matched against * so the value of $2 doesn't really matter. One could, in the context described in the Wiki, also write
#!/bin/sh
case $1 in
pre)
echo "Going to $2..."
;;
post)
echo "Waking up from $2..."
;;
esac
But there might be cases where suspend, hibernate or hybrid (the possible values for $2) are relevant, so it's just a general pattern here.
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
3
maybe$1ispre/heatand$2isovenin which case your code would not match, but the original would ;-)
– mosvy
Dec 22 '18 at 17:19
1
@mosvy True. But in the context of the script as explained on the Arch Wiki page linked in the question that's something which "should not happen". Haha.
– nohillside
Dec 22 '18 at 17:23
They would not be equivalent in cases where$1ispre/something.
– Stéphane Chazelas
Dec 22 '18 at 17:58
add a comment |
There is nothing special here. The syntax for case is
case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
In the example in the question, word is built by combining $1, / and $2. / doesn't have a special meaning at all, it's just a character.
PS: Practically the usage is a bit strange, as the $2 part afterwards gets matched against * so the value of $2 doesn't really matter. One could, in the context described in the Wiki, also write
#!/bin/sh
case $1 in
pre)
echo "Going to $2..."
;;
post)
echo "Waking up from $2..."
;;
esac
But there might be cases where suspend, hibernate or hybrid (the possible values for $2) are relevant, so it's just a general pattern here.
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
3
maybe$1ispre/heatand$2isovenin which case your code would not match, but the original would ;-)
– mosvy
Dec 22 '18 at 17:19
1
@mosvy True. But in the context of the script as explained on the Arch Wiki page linked in the question that's something which "should not happen". Haha.
– nohillside
Dec 22 '18 at 17:23
They would not be equivalent in cases where$1ispre/something.
– Stéphane Chazelas
Dec 22 '18 at 17:58
add a comment |
There is nothing special here. The syntax for case is
case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
In the example in the question, word is built by combining $1, / and $2. / doesn't have a special meaning at all, it's just a character.
PS: Practically the usage is a bit strange, as the $2 part afterwards gets matched against * so the value of $2 doesn't really matter. One could, in the context described in the Wiki, also write
#!/bin/sh
case $1 in
pre)
echo "Going to $2..."
;;
post)
echo "Waking up from $2..."
;;
esac
But there might be cases where suspend, hibernate or hybrid (the possible values for $2) are relevant, so it's just a general pattern here.
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
There is nothing special here. The syntax for case is
case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
In the example in the question, word is built by combining $1, / and $2. / doesn't have a special meaning at all, it's just a character.
PS: Practically the usage is a bit strange, as the $2 part afterwards gets matched against * so the value of $2 doesn't really matter. One could, in the context described in the Wiki, also write
#!/bin/sh
case $1 in
pre)
echo "Going to $2..."
;;
post)
echo "Waking up from $2..."
;;
esac
But there might be cases where suspend, hibernate or hybrid (the possible values for $2) are relevant, so it's just a general pattern here.
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
edited Dec 22 '18 at 17:41
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
answered Dec 22 '18 at 16:27
nohillsidenohillside
2,3901019
2,3901019
3
maybe$1ispre/heatand$2isovenin which case your code would not match, but the original would ;-)
– mosvy
Dec 22 '18 at 17:19
1
@mosvy True. But in the context of the script as explained on the Arch Wiki page linked in the question that's something which "should not happen". Haha.
– nohillside
Dec 22 '18 at 17:23
They would not be equivalent in cases where$1ispre/something.
– Stéphane Chazelas
Dec 22 '18 at 17:58
add a comment |
3
maybe$1ispre/heatand$2isovenin which case your code would not match, but the original would ;-)
– mosvy
Dec 22 '18 at 17:19
1
@mosvy True. But in the context of the script as explained on the Arch Wiki page linked in the question that's something which "should not happen". Haha.
– nohillside
Dec 22 '18 at 17:23
They would not be equivalent in cases where$1ispre/something.
– Stéphane Chazelas
Dec 22 '18 at 17:58
3
3
maybe
$1 is pre/heat and $2 is oven in which case your code would not match, but the original would ;-)– mosvy
Dec 22 '18 at 17:19
maybe
$1 is pre/heat and $2 is oven in which case your code would not match, but the original would ;-)– mosvy
Dec 22 '18 at 17:19
1
1
@mosvy True. But in the context of the script as explained on the Arch Wiki page linked in the question that's something which "should not happen". Haha.
– nohillside
Dec 22 '18 at 17:23
@mosvy True. But in the context of the script as explained on the Arch Wiki page linked in the question that's something which "should not happen". Haha.
– nohillside
Dec 22 '18 at 17:23
They would not be equivalent in cases where
$1 is pre/something.– Stéphane Chazelas
Dec 22 '18 at 17:58
They would not be equivalent in cases where
$1 is pre/something.– Stéphane Chazelas
Dec 22 '18 at 17:58
add a comment |
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it matches the
/inpre/*andpost/*– ctrl-alt-delor
Dec 22 '18 at 17:46
It is a trick to test $1 and $2 at the same time.
– Thorbjørn Ravn Andersen
Dec 23 '18 at 1:04