Update required programs check to use tr command instead of truncate command

[manojrkrish]

Issue
I have tried to use docker-bench-security in a custom Linux environment where 'tr' command is not available. Running docker-bench-security in this environment results in multiple warning messages in different checks.

./functions/helper_lib.sh: line 82: tr: command not found
./functions/helper_lib.sh: line 52: tr: command not found
./functions/helper_lib.sh: line 120: tr: command not found
./tests/1_host_configuration.sh: line 645: tr: command not found
./tests/5_container_runtime.sh: line 120: tr: command not found

Cause
These warnings are logged as 'tr' command is missing in this environment. Though docker-bench-security has done checks for required programs, its checking for 'truncate' command instead 'tr' command https://github.com/docker/docker-bench-security/blob/master/docker-bench-security.sh#L27.

$ truncate --help
Usage: truncate OPTION... FILE...
Shrink or extend the size of each FILE to the specified size

$ tr --help
Usage: tr [OPTION]... SET1 [SET2]
Translate, squeeze, and/or delete characters from standard input,
writing to standard output.

Suggestion
Docker bench security can check for 'tr' command in the required programs list instead of 'truncate' command.

Docker Bench Version

# --------------------------------------------------------------------------------------------
# Docker Bench for Security v1.5.0
#
# Docker, Inc. (c) 2015-2023
#
# Checks for dozens of common best-practices around deploying Docker containers in production.
# Based on the CIS Docker Benchmark 1.5.0.
# --------------------------------------------------------------------------------------------

Docker Version

Version:            20.10.14
API version:      1.41 (minimum version 1.12)
Go version:       go1.20.4

[konstruktoid]

Nice catch @manojrkrish
Will be fixed shortly

[konstruktoid]

Please test again

[manojrkrish]

Thanks @konstruktoid , works as expected now, error thrown when 'tr' command not found. Thanks for quick fix.

Required program not found: tr