Tests setup

The internal LTP library provides a set of features that permits to customize tests behavior by setting environment variables and using specific tests arguments.

Library environment variables

Following environment variables are expected to be set by LTP users. Therefore, with some exceptions, they have LTP_ prefix. Environment variables with TST_ prefix are used inside LTP shell API and should not be set by users.

Variable	Note
KCONFIG_PATH	The path to the kernel config file, (if not set, it tries the usual paths /boot/config-RELEASE or /proc/config.gz)
KCONFIG_SKIP_CHECK	Skip kernel config check if variable set (not set by default)
LTPROOT	Prefix for installed LTP. Should be always set, since some tests need it to use data files (LTP_DATAROOT). LTP is by default installed into /opt/ltp
LTP_COLORIZE_OUTPUT	By default LTP colorizes it’s output unless it’s redirected to a pipe or file. Force colorized output behavior: y or 1: always colorize, n or 0: never colorize.
LTP_DEV	Path to the block device to be used. C Language: .needs_device = 1. Shell language: TST_NEEDS_DEVICE=1.
LTP_REPRODUCIBLE_OUTPUT	When set to 1 or y suppress printing TINFO and TDEBUG messages and discards the actual content of the other messages printed by the test (suitable for a reproducible output).
LTP_SINGLE_FS_TYPE	Specifies single filesystem to run the test on instead all supported (for tests with .all_filesystems).
LTP_FORCE_SINGLE_FS_TYPE	Testing only. Behaves like LTP_SINGLE_FS_TYPE but ignores test skiplists.
LTP_DEV_FS_TYPE	Filesystem used for testing (default: ext2).
LTP_TIMEOUT_MUL	Multiplies timeout, must be number >= 0.1 (> 1 is useful for slow machines to avoid unexpected timeout). It’s mainly for shell API, which does not have LTP_RUNTIME_MUL. In C API it scales the default 30 sec safety margin, probably LTP_RUNTIME_MUL should be used instead.
LTP_RUNTIME_MUL	Multiplies maximal test iteration runtime. Tests that run for more than a second or two are capped on runtime. You can scale the default runtime both up and down with this multiplier. This is not yet implemented in the shell API.
LTP_USR_UID, LTP_USR_GID	Set UID and GID of nobody user for LTP shell API, see testcases/lib/tst_runas.c.
LTP_VIRT_OVERRIDE	Overrides virtual machine detection in the test library. Setting it to empty string, tells the library that system is not a virtual machine. Other possible values are kvm, xen, zvm and microsoft that describe different types supervisors.
PATH	It’s required to adjust path: PATH="$PATH:$LTPROOT/testcases/bin"
TMPDIR	Base directory for template directory (C language: .needs_tmpdir = 1 and shell: TST_NEEDS_TMPDIR=1). Must be an absolute path (default: ‘/tmp’).
LTP_NO_CLEANUP	Disable running test cleanup (defined in TST_CLEANUP). Shell API only.
LTP_DEBUG	Enable debug info (value 1 (y) or 2 for more verbose level). Equivalent of the -D parameter (see Debugging).

Test specific environment variables

Tests	Variable	Note
IMA	LTP_IMA_LOAD_POLICY=1	Load IMA example policy, see testcases/kernel/security/integrity/ima/README.md.
NFS	LTP_NFS_NETNS_USE_LO=1	NFS traffic will go through loopback interface instead of ltp_ns_veth* netns interfaces (useful for debugging whether test failures are related to veth/netns).
Network	various	See testcases/network/README.md.

Test execution time and timeout

The limit on how long a test can run does compose of two parts: runtime and timeout. The limit does apply to a single test variant. That means, for example, that tests which run for all available filesystems will apply this limit for a single filesystem only.

The runtime is a cap on how long the run() function can take and for most testcases this part is set to zero. For tests that do run for more than a second or two the runtime has to be defined and the run() function has to check actively how much runtime is left.

Test runtime can be scaled up and down with LTP_RUNTIME_MUL environment variable or set on a command-line by the -I parameter. However, setting the runtime too low will cause long running tests to exit prematurely, possibly before having a chance to actually test anything.

The timeout is a limit for test setup and cleanup and it’s also a safety margin for the runtime accounting. It’s currently set to 30 seconds but it may change later. If your target machine is too slow, it can be scaled up with the LTP_TIMEOUT_MUL environment variable.