LPI Updated 101-500 Exam Questions and Answers by alaia

 When using rpm --verify to check files created during the installation of RPM packages, the following information is taken into consideration:

• Timestamps. RPM compares the modification time of the installed files with the original time stored in the RPM database. If the file has been modified after installation, the timestamp will differ and RPM will report it with an M flag1.
• MD5 checksums. RPM calculates the MD5 checksum of the installed files and compares it with the original checksum stored in the RPM database. If the file has been altered in any way, the checksum will differ and RPM will report it with an 5 flag1.
• File sizes. RPM compares the size of the installed files with the original size stored in the RPM database. If the file has been truncated or appended, the size will differ and RPM will report it with an S flag1.

RPM does not take into consideration the following information:

• Inodes. RPM does not check the inode number of the installed files, as it is not a reliable indicator of file identity. The inode number can change if the file is moved, copied, or restored from a backup2.
• GnuPG signatures. RPM does not verify the GnuPG signatures of the installed files, as they are not part of the RPM package format. The GnuPG signatures are used to verify the authenticity and integrity of the RPM package files before installation, not after3.

References:

• Using RPM to Verify Installed Packages
• inode(7) - Linux manual page
• RPM and GPG: How to verify Linux packages before installing them

 The environment variable LD_LIBRARY_PATH is used to tell the dynamic linker to look in a specific directory for some of a program’s shared libraries. It is a colon-separated list of directories that are searched by the dynamic linker when looking for a shared library to load1. The directories are searched in the order they are mentioned in. For example, if we have a program that depends on a shared library libfoo.so that is located in /home/user/build/lib, we can run the program with:

LD_LIBRARY_PATH=/home/user/build/lib ./program

This will instruct the dynamic linker to search for libfoo.so in /home/user/build/lib before the default directories. The environment variable LD_LIBRARY_PATH can also be appended to an existing value with the += operator, for example:

LD_LIBRARY_PATH+=:/home/user/build/lib

This will add /home/user/build/lib to the end of the LD_LIBRARY_PATH list. The other options are not valid environment variables for the dynamic linker. LD_LOAD_PATH, LD_LIB_PATH, and LD_SHARE_PATH are not recognized by the dynamic linker. LD_RUN_PATH is a linker option that can be used to embed a librarysearch path in the executable at link time, but it is not an environment variable that can be set or modified at run time2. References:

• LPI Exam 101 Detailed Objectives, section 1.101.3
• ld-linux(8) — Linux manual page
• Setting the dynamic linker with an environment variable - narkive

 The RPM command that will output the name of the package which supplied the file /etc/exports is rpm -qf /etc/exports. This command will query the RPM database and find the package that owns or provides the file /etc/exports1. The output will show the package name, version, release, and architecture. For example:

The other options are incorrect for the following reasons:

• rpm -F /etc/exports. This command will try to freshen or upgrade the package that contains the file /etc/exports, if it is already installed2. This command will not output the package name, but rather install the latest version of the package from a specified source. For example:

• rpm -Kl /etc/exports. This command is not valid, as RPM does not have a -Kl option. The -K option is used to verify the signatures of the RPM package files, not the installed files3. The -l option is used to list the files in a package, not to query the package name. For example:

• rpm -qp /etc/exports. This command will try to query the package information of the file /etc/exports, as if it was an RPM package file. This command will not output the package name, but rather an error message, as /etc/exports is not a valid RPM package file. For example:

• rpm -qi /etc/exports. This command will try to query the information of the package /etc/exports, as if it was an installed package name. This command will not output the package name, but rather an error message, as /etc/exports is not a valid package name. For example:

References:

• How to find which rpm package provides a specific file or library in RHEL / CentOS
• rpm(8) - Linux manual page
• rpm(8) - Linux manual page
• [rpm(8) - Linux manual page]

The /tmp directory should be on a separate partition if possible because it is world writable. This means that any user can create, modify, or delete files and directories in /tmp. This can pose a risk of filling up the / partition, which can cause system instability or failure. By having /tmp on a separate partition, we can limit the amount of disk space that can be used by temporary files and prevent users from affecting the / partition. The /tmp directory is also a common target for malicious attacks, so having it on a separate partition can improve the security and isolation of the system. The /tmp directory is one of the few directories that are world writable by default, according to the Filesystem Hierarchy Standard (FHS)1. The other directories that are usually world writable are /var/tmp and /var/lock, which are also used for temporary or lock files. However, these directories are not as frequently used or as large as /tmp, so they are less likely to fill up the / partition. The /tmp directory also has the sticky bit set, which means that only the owner of a file or directory can delete or rename it2. This prevents users from deleting or modifying other users’ files in /tmp. However, this does not prevent users from creating new files or directories in /tmp, which can still consume disk space and resources. Therefore, it is advisable to have /tmp on a separate partition if possible. References:

• Filesystem Hierarchy Standard
• Sticky bit - Wikipedia