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Bash echo $-1 prints hb1. Why?
Meaning of a hyphen as a special parameter?Why did BASH print “bash: cd: write error: Success”?Explain this bash script: echo “$1##*.”why 'echo --help' doesn't give me help page of echo?Bash - syntax in echoNested echo command in backticksWhy does `bash -c 'echo $0 ' ` output “bash”?bash script to echo wan ipWhy is echo $SHELL always showing /bin/bash?bash - echo prints to the terminalCan't pipe from echo to bash built-in read?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
If I ask bash to echo the -1th argument it prints hb1:
echo $-1
hb1
Why? What is it accessing?
bash arguments
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
add a comment |
If I ask bash to echo the -1th argument it prints hb1:
echo $-1
hb1
Why? What is it accessing?
bash arguments
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
1
$-gets the current shell options (which is apparently "hb"). What did you expect it to do?
– Gordon Davisson
9 hours ago
I thought it might loop round like some arrays do. Thanks.
– Neil
9 hours ago
Possible duplicate of Meaning of a hyphen as a special parameter?
– muru
9 hours ago
add a comment |
If I ask bash to echo the -1th argument it prints hb1:
echo $-1
hb1
Why? What is it accessing?
bash arguments
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
If I ask bash to echo the -1th argument it prints hb1:
echo $-1
hb1
Why? What is it accessing?
bash arguments
bash arguments
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
edited 6 hours ago
Jeff Schaller♦
47.1k11 gold badges68 silver badges153 bronze badges
47.1k11 gold badges68 silver badges153 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
asked 9 hours ago
NeilNeil
1083 bronze badges
1083 bronze badges
1
$-gets the current shell options (which is apparently "hb"). What did you expect it to do?
– Gordon Davisson
9 hours ago
I thought it might loop round like some arrays do. Thanks.
– Neil
9 hours ago
Possible duplicate of Meaning of a hyphen as a special parameter?
– muru
9 hours ago
add a comment |
1
$-gets the current shell options (which is apparently "hb"). What did you expect it to do?
– Gordon Davisson
9 hours ago
I thought it might loop round like some arrays do. Thanks.
– Neil
9 hours ago
Possible duplicate of Meaning of a hyphen as a special parameter?
– muru
9 hours ago
1
1
$- gets the current shell options (which is apparently "hb"). What did you expect it to do?– Gordon Davisson
9 hours ago
$- gets the current shell options (which is apparently "hb"). What did you expect it to do?– Gordon Davisson
9 hours ago
I thought it might loop round like some arrays do. Thanks.
– Neil
9 hours ago
I thought it might loop round like some arrays do. Thanks.
– Neil
9 hours ago
Possible duplicate of Meaning of a hyphen as a special parameter?
– muru
9 hours ago
Possible duplicate of Meaning of a hyphen as a special parameter?
– muru
9 hours ago
add a comment |
1 Answer
1
active
oldest
votes
You are not asking it to print the 1st argument, that would be: $1.
What you are asking for is a special parameter:
-
(
$-, a hyphen.) Expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).
So your options are: hb
Then you see the 1 you've added is printed afterwards (hence hb1).
If you are looking to get the last argument (Not sure if that is what you meant by -1 argument), you can use Shell Parameter Expansion in the following form:
$ set -- one two three
$ echo "$@: -1"
three
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
4
$!#is also the value of the last parameter, using indirect expansion.
– glenn jackman
9 hours ago
1
Hmmm:$@:~0andeval echo $$#are also the last argument. :-)
– Isaac
8 hours ago
add a comment |
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1 Answer
1
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oldest
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active
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votes
You are not asking it to print the 1st argument, that would be: $1.
What you are asking for is a special parameter:
-
(
$-, a hyphen.) Expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).
So your options are: hb
Then you see the 1 you've added is printed afterwards (hence hb1).
If you are looking to get the last argument (Not sure if that is what you meant by -1 argument), you can use Shell Parameter Expansion in the following form:
$ set -- one two three
$ echo "$@: -1"
three
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
4
$!#is also the value of the last parameter, using indirect expansion.
– glenn jackman
9 hours ago
1
Hmmm:$@:~0andeval echo $$#are also the last argument. :-)
– Isaac
8 hours ago
add a comment |
You are not asking it to print the 1st argument, that would be: $1.
What you are asking for is a special parameter:
-
(
$-, a hyphen.) Expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).
So your options are: hb
Then you see the 1 you've added is printed afterwards (hence hb1).
If you are looking to get the last argument (Not sure if that is what you meant by -1 argument), you can use Shell Parameter Expansion in the following form:
$ set -- one two three
$ echo "$@: -1"
three
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
4
$!#is also the value of the last parameter, using indirect expansion.
– glenn jackman
9 hours ago
1
Hmmm:$@:~0andeval echo $$#are also the last argument. :-)
– Isaac
8 hours ago
add a comment |
You are not asking it to print the 1st argument, that would be: $1.
What you are asking for is a special parameter:
-
(
$-, a hyphen.) Expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).
So your options are: hb
Then you see the 1 you've added is printed afterwards (hence hb1).
If you are looking to get the last argument (Not sure if that is what you meant by -1 argument), you can use Shell Parameter Expansion in the following form:
$ set -- one two three
$ echo "$@: -1"
three
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
You are not asking it to print the 1st argument, that would be: $1.
What you are asking for is a special parameter:
-
(
$-, a hyphen.) Expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).
So your options are: hb
Then you see the 1 you've added is printed afterwards (hence hb1).
If you are looking to get the last argument (Not sure if that is what you meant by -1 argument), you can use Shell Parameter Expansion in the following form:
$ set -- one two three
$ echo "$@: -1"
three
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
answered 9 hours ago
Jesse_bJesse_b
17.1k3 gold badges42 silver badges84 bronze badges
17.1k3 gold badges42 silver badges84 bronze badges
4
$!#is also the value of the last parameter, using indirect expansion.
– glenn jackman
9 hours ago
1
Hmmm:$@:~0andeval echo $$#are also the last argument. :-)
– Isaac
8 hours ago
add a comment |
4
$!#is also the value of the last parameter, using indirect expansion.
– glenn jackman
9 hours ago
1
Hmmm:$@:~0andeval echo $$#are also the last argument. :-)
– Isaac
8 hours ago
4
4
$!# is also the value of the last parameter, using indirect expansion.– glenn jackman
9 hours ago
$!# is also the value of the last parameter, using indirect expansion.– glenn jackman
9 hours ago
1
1
Hmmm:
$@:~0 and eval echo $$# are also the last argument. :-)– Isaac
8 hours ago
Hmmm:
$@:~0 and eval echo $$# are also the last argument. :-)– Isaac
8 hours ago
add a comment |
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1
$-gets the current shell options (which is apparently "hb"). What did you expect it to do?– Gordon Davisson
9 hours ago
I thought it might loop round like some arrays do. Thanks.
– Neil
9 hours ago
Possible duplicate of Meaning of a hyphen as a special parameter?
– muru
9 hours ago