Bash: Use raw binary in variable as executable?
I'd like to create a variable containing binary data, then execute in a command. Example:
#!/bin/bash
var="$(cat /bin/sleep)"
"$var" 9999
linux bash shell ubuntu variable
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I'd like to create a variable containing binary data, then execute in a command. Example:
#!/bin/bash
var="$(cat /bin/sleep)"
"$var" 9999
linux bash shell ubuntu variable
add a comment |
I'd like to create a variable containing binary data, then execute in a command. Example:
#!/bin/bash
var="$(cat /bin/sleep)"
"$var" 9999
linux bash shell ubuntu variable
I'd like to create a variable containing binary data, then execute in a command. Example:
#!/bin/bash
var="$(cat /bin/sleep)"
"$var" 9999
linux bash shell ubuntu variable
linux bash shell ubuntu variable
asked Nov 17 '18 at 23:59
user321517user321517
202
202
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1 Answer
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You cannot execute a variable like that because:
- the kernel executes files,
- the shell can execute command lines stored in variables, but it cannot interpret binary data
- storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)
- even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable
So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You cannot execute a variable like that because:
- the kernel executes files,
- the shell can execute command lines stored in variables, but it cannot interpret binary data
- storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)
- even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable
So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.
add a comment |
You cannot execute a variable like that because:
- the kernel executes files,
- the shell can execute command lines stored in variables, but it cannot interpret binary data
- storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)
- even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable
So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.
add a comment |
You cannot execute a variable like that because:
- the kernel executes files,
- the shell can execute command lines stored in variables, but it cannot interpret binary data
- storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)
- even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable
So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.
You cannot execute a variable like that because:
- the kernel executes files,
- the shell can execute command lines stored in variables, but it cannot interpret binary data
- storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)
- even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable
So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.
answered Nov 18 '18 at 0:52
![](https://i.stack.imgur.com/xNPjb.png?s=32&g=1)
![](https://i.stack.imgur.com/xNPjb.png?s=32&g=1)
murumuru
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