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zsh and POSIX equivalent of bash's `var>&1`
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Is there an equivalent of var>&1 in zsh?
The bash manual says:
Each redirection that may be preceded by a file descriptor number may instead be preceded by a word of the form
varname. In this case, for each redirection operator except>&-and<&-, the shell will allocate a file descriptor greater than 10 and assign it tovarname. If>&-or<&-is preceded byvarname, the value of varname defines the file descriptor to close.
An example usage of this is capturing STDERR from a command:
error=$( ls -ld /XXXX /bin 1>&$tmp ; 2>&1); tmp>&1
How would one do the same in zsh, and also in POSIX-land?
bash shell zsh posix
asked 43 mins ago
Tom Hale
5,98122776
add a comment |Â
up vote
2
down vote
favorite
Is there an equivalent of var>&1 in zsh?
The bash manual says:
Each redirection that may be preceded by a file descriptor number may instead be preceded by a word of the form
varname. In this case, for each redirection operator except>&-and<&-, the shell will allocate a file descriptor greater than 10 and assign it tovarname. If>&-or<&-is preceded byvarname, the value of varname defines the file descriptor to close.
An example usage of this is capturing STDERR from a command:
error=$( ls -ld /XXXX /bin 1>&$tmp ; 2>&1); tmp>&1
How would one do the same in zsh, and also in POSIX-land?
bash shell zsh posix
asked 43 mins ago
Tom Hale
5,98122776
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
Is there an equivalent of var>&1 in zsh?
The bash manual says:
Each redirection that may be preceded by a file descriptor number may instead be preceded by a word of the form
varname. In this case, for each redirection operator except>&-and<&-, the shell will allocate a file descriptor greater than 10 and assign it tovarname. If>&-or<&-is preceded byvarname, the value of varname defines the file descriptor to close.
An example usage of this is capturing STDERR from a command:
error=$( ls -ld /XXXX /bin 1>&$tmp ; 2>&1); tmp>&1
How would one do the same in zsh, and also in POSIX-land?
bash shell zsh posix
asked 43 mins ago
Tom Hale
5,98122776
Is there an equivalent of var>&1 in zsh?
The bash manual says:
Each redirection that may be preceded by a file descriptor number may instead be preceded by a word of the form
varname. In this case, for each redirection operator except>&-and<&-, the shell will allocate a file descriptor greater than 10 and assign it tovarname. If>&-or<&-is preceded byvarname, the value of varname defines the file descriptor to close.
An example usage of this is capturing STDERR from a command:
error=$( ls -ld /XXXX /bin 1>&$tmp ; 2>&1); tmp>&1
How would one do the same in zsh, and also in POSIX-land?
bash shell zsh posix
bash shell zsh posix
asked 43 mins ago
Tom Hale
5,98122776
asked 43 mins ago
Tom Hale
5,98122776
asked 43 mins ago
Tom Hale
5,98122776
asked 43 mins ago
Tom Hale
5,98122776
asked 43 mins ago
Tom Hale
5,98122776
5,98122776
add a comment |Â
add a comment |Â
1 Answer
1
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up vote
3
down vote
Support for var>... was added to ksh93, bash and zsh at the same time on a suggestion of a zsh developer. The var>... operator works in zsh, but not for compound commands.
Also note that while in:
cmd 3>&1
The fd 3 is open only for cmd, in
cmd var>&1
The dynamically allocated fd (stored in $var) remains open after cmd returns in both zsh and bash. That operator is mostly designed to be used with exec (see also sysopen in zsh for a more straightforward interface to the open() system call).
So you code above is missing some code to close that fd in bash.
So here you could do:
exec tmp>&1
errors=$(exec 2>&1 >&$tmp tmp>&-; ls -ld /x /bin | tr o Z)
exec tmp>&-
Which would work in bash, zsh and ksh93 and not leak a fd.
But you don't need a dynamically allocated fd here, just use for instance the fd 3 which is not used in that code:
errors=$(exec 2>&1 >&3 3>&-; ls -ld /x /bin 3>&1
Which would work in any Bourne-like shell.
answered 25 mins ago
Stéphane Chazelas
286k53528867
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
Support for var>... was added to ksh93, bash and zsh at the same time on a suggestion of a zsh developer. The var>... operator works in zsh, but not for compound commands.
Also note that while in:
cmd 3>&1
The fd 3 is open only for cmd, in
cmd var>&1
The dynamically allocated fd (stored in $var) remains open after cmd returns in both zsh and bash. That operator is mostly designed to be used with exec (see also sysopen in zsh for a more straightforward interface to the open() system call).
So you code above is missing some code to close that fd in bash.
So here you could do:
exec tmp>&1
errors=$(exec 2>&1 >&$tmp tmp>&-; ls -ld /x /bin | tr o Z)
exec tmp>&-
Which would work in bash, zsh and ksh93 and not leak a fd.
But you don't need a dynamically allocated fd here, just use for instance the fd 3 which is not used in that code:
errors=$(exec 2>&1 >&3 3>&-; ls -ld /x /bin 3>&1
Which would work in any Bourne-like shell.
answered 25 mins ago
Stéphane Chazelas
286k53528867
add a comment |Â
up vote
3
down vote
Support for var>... was added to ksh93, bash and zsh at the same time on a suggestion of a zsh developer. The var>... operator works in zsh, but not for compound commands.
Also note that while in:
cmd 3>&1
The fd 3 is open only for cmd, in
cmd var>&1
The dynamically allocated fd (stored in $var) remains open after cmd returns in both zsh and bash. That operator is mostly designed to be used with exec (see also sysopen in zsh for a more straightforward interface to the open() system call).
So you code above is missing some code to close that fd in bash.
So here you could do:
exec tmp>&1
errors=$(exec 2>&1 >&$tmp tmp>&-; ls -ld /x /bin | tr o Z)
exec tmp>&-
Which would work in bash, zsh and ksh93 and not leak a fd.
But you don't need a dynamically allocated fd here, just use for instance the fd 3 which is not used in that code:
errors=$(exec 2>&1 >&3 3>&-; ls -ld /x /bin 3>&1
Which would work in any Bourne-like shell.
answered 25 mins ago
Stéphane Chazelas
286k53528867
add a comment |Â
up vote
3
down vote
up vote
3
down vote
Support for var>... was added to ksh93, bash and zsh at the same time on a suggestion of a zsh developer. The var>... operator works in zsh, but not for compound commands.
Also note that while in:
cmd 3>&1
The fd 3 is open only for cmd, in
cmd var>&1
The dynamically allocated fd (stored in $var) remains open after cmd returns in both zsh and bash. That operator is mostly designed to be used with exec (see also sysopen in zsh for a more straightforward interface to the open() system call).
So you code above is missing some code to close that fd in bash.
So here you could do:
exec tmp>&1
errors=$(exec 2>&1 >&$tmp tmp>&-; ls -ld /x /bin | tr o Z)
exec tmp>&-
Which would work in bash, zsh and ksh93 and not leak a fd.
But you don't need a dynamically allocated fd here, just use for instance the fd 3 which is not used in that code:
errors=$(exec 2>&1 >&3 3>&-; ls -ld /x /bin 3>&1
Which would work in any Bourne-like shell.
answered 25 mins ago
Stéphane Chazelas
286k53528867
Support for var>... was added to ksh93, bash and zsh at the same time on a suggestion of a zsh developer. The var>... operator works in zsh, but not for compound commands.
Also note that while in:
cmd 3>&1
The fd 3 is open only for cmd, in
cmd var>&1
The dynamically allocated fd (stored in $var) remains open after cmd returns in both zsh and bash. That operator is mostly designed to be used with exec (see also sysopen in zsh for a more straightforward interface to the open() system call).
So you code above is missing some code to close that fd in bash.
So here you could do:
exec tmp>&1
errors=$(exec 2>&1 >&$tmp tmp>&-; ls -ld /x /bin | tr o Z)
exec tmp>&-
Which would work in bash, zsh and ksh93 and not leak a fd.
But you don't need a dynamically allocated fd here, just use for instance the fd 3 which is not used in that code:
errors=$(exec 2>&1 >&3 3>&-; ls -ld /x /bin 3>&1
Which would work in any Bourne-like shell.
answered 25 mins ago
Stéphane Chazelas
286k53528867
edited 17 mins ago
answered 25 mins ago
Stéphane Chazelas
286k53528867
answered 25 mins ago
Stéphane Chazelas
286k53528867
answered 25 mins ago
Stéphane Chazelas
286k53528867
286k53528867
add a comment |Â
add a comment |Â
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