6.27. Libcap-2.27

#### Linux From Scratch - Version 9.0-systemd

### Chapter 6. Installing Basic System Software

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# 6.27. Libcap-2.27

The Libcap package implements the user-space interfaces to the POSIX 1003.1e capabilities available in Linux kernels. These capabilities are a partitioning of the all powerful root privilege into a set of distinct privileges.

Approximate build time: less than 0.1 SBU
Required disk space: 1.5 MB

## 6.27.1. Installation of Libcap

Prevent a static library from being installed:

    sed -i '/install.*STALIBNAME/d' libcap/Makefile

Compile the package:

    make

This package does not come with a test suite.

Install the package:

    make RAISE_SETFCAP=no lib=lib prefix=/usr install
    chmod -v 755 /usr/lib/libcap.so.2.27

The meaning of the make option:

`RAISE_SETFCAP=no`

  This parameter skips trying to use setcap on itself. This avoids an installation error if the kernel or file system does not support extended capabilities.

`lib=lib`

  This parameter installs the library in `$prefix/lib` rather than `$prefix/lib64` on x86_64. It has no effect on x86.

The shared library needs to be moved to `/lib`, and as a result the `.so` file in `/usr/lib` will need to be recreated:

    mv -v /usr/lib/libcap.so.* /lib
    ln -sfv ../../lib/$(readlink /usr/lib/libcap.so) /usr/lib/libcap.so

## 6.27.2. Contents of Libcap

Installed programs: capsh, getcap, getpcaps, and setcap
Installed library: libcap.so

### Short Descriptions

capsh | A shell wrapper to explore and constrain capability support
getcap | Examines file capabilities
getpcaps | Displays the capabilities on the queried process(es)
setcap | Sets file capabilities
`libcap` | Contains the library functions for manipulating POSIX 1003.1e capabilities

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