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0 pointsblenderob1y ago0 comments

What about compiled binaries that for one reason or another is doing an execve() on "/usr/bin/cmp" or some such thing? Do you propose changing every script and every binary on earth that expects Busybox to be a POSIXy, Unixy environment?

0 comments

pzmarzly1y ago

On Unixes it doesn't matter if /usr/bin/cmp is a script or a compiled binary. If the script has correct shebang, kernel takes care of executing it.

oguz-ismail1y ago

Shebangs are not part of the UNIX specification. What happens if an executable starts with `#!' is implementation-defined.

account421y ago

UNIX/POSIX doesn't specify an executable format at all

immibis1y ago

is being able to run busybox part of that specification? Linux ELF files are tagged for Linux OS, not generic Unix OS.

1 more reply

sophacles1y ago

No you make this script:

   #!/bin/sh
   exec /bin/busybox cmp

And place it at /usr/bin/cmp

teddyh1y ago

Surely you mean

  #!/bin/sh
  exec /bin/busybox cmp "$@"

oguz-ismail1y ago

`#!/bin/sh' makes this less portable than it could be, if /bin/sh doesn't exists on my system it won't work, for example. Remove that line and it'll work everywhere.

1 more reply

alerighi1y ago

So now to execute a program that could have been a direct run you have to fire up a shell, have it parse the file, and execute the instruction? Not really a great thing...

Plus, you have to know the absolute path of the executable busybox, not something you always know in advance.

sophacles1y ago

You're not wrong about the extra execution of shell, although a lightweight shell like ash or dash doesn't have a huge overhead.

But realistically, the only people that need to worry about the actual location of the busybox executable are the people who write the install script - it would take that as an argument or variable and spit out all the little scripts as an automated process. The current installer already has to do most of this work as part of setting up the relevant links anyway.

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0 comments

pzmarzly1y ago

On Unixes it doesn't matter if /usr/bin/cmp is a script or a compiled binary. If the script has correct shebang, kernel takes care of executing it.

oguz-ismail1y ago

Shebangs are not part of the UNIX specification. What happens if an executable starts with `#!' is implementation-defined.

account421y ago

UNIX/POSIX doesn't specify an executable format at all

immibis1y ago

is being able to run busybox part of that specification? Linux ELF files are tagged for Linux OS, not generic Unix OS.

1 more reply

sophacles1y ago

No you make this script:

   #!/bin/sh
   exec /bin/busybox cmp

And place it at /usr/bin/cmp

teddyh1y ago

Surely you mean

  #!/bin/sh
  exec /bin/busybox cmp "$@"

oguz-ismail1y ago

`#!/bin/sh' makes this less portable than it could be, if /bin/sh doesn't exists on my system it won't work, for example. Remove that line and it'll work everywhere.

1 more reply

alerighi1y ago

So now to execute a program that could have been a direct run you have to fire up a shell, have it parse the file, and execute the instruction? Not really a great thing...

Plus, you have to know the absolute path of the executable busybox, not something you always know in advance.

sophacles1y ago

You're not wrong about the extra execution of shell, although a lightweight shell like ash or dash doesn't have a huge overhead.

j / k navigate · click thread line to collapse