Bash: Use raw binary in variable as executable?

up vote
2
down vote

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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

asked Nov 17 at 23:59

user321517

202

New contributor

add a comment |

up vote
2
down vote

favorite

I'd like to create a variable containing binary data, then execute in a command. Example:

#!/bin/bash

var="$(cat /bin/sleep)"

"$var" 9999

asked Nov 17 at 23:59

user321517

202

New contributor

add a comment |

up vote
2
down vote

favorite

I'd like to create a variable containing binary data, then execute in a command. Example:

#!/bin/bash

var="$(cat /bin/sleep)"

"$var" 9999

asked Nov 17 at 23:59

user321517

202

New contributor

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

asked Nov 17 at 23:59

user321517

202

New contributor

asked Nov 17 at 23:59

user321517

202

New contributor

asked Nov 17 at 23:59

user321517

202

New contributor

asked Nov 17 at 23:59

user321517

202

asked Nov 17 at 23:59

user321517

202

New contributor

user321517 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

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1 Answer
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3
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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.

answered Nov 18 at 0:52

muru

35.1k581154

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1 Answer
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active

oldest

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1 Answer
1

active

oldest

votes

up vote
3
down vote

accepted

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 at 0:52

muru

35.1k581154

add a comment |

up vote
3
down vote

accepted

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 at 0:52

muru

35.1k581154

add a comment |

up vote
3
down vote

accepted

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 at 0:52

muru

35.1k581154

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 at 0:52

muru

35.1k581154

answered Nov 18 at 0:52

muru

35.1k581154

answered Nov 18 at 0:52

muru

35.1k581154

answered Nov 18 at 0:52

muru

35.1k581154

add a comment |

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