Bash Library

A library of re-usable bash scripts

Overview

This Bash Library includes the following features:

• implements a client that issues HTTP conditional requests (RFC 7232)
• monitors an arbitrary HTTP resource for responsiveness (see doc: http_response_stats.md)
• monitors a compressed HTTP resource for responsiveness and integrity (see doc: http_compression_stats.md)
• includes a compatibility layer (Linux and Mac OS)
• has a built-in logging facility
• is cron-friendly

For detailed information about one of the tools, consult the tool's online help. For example, after installing the library, type:

$ $BIN_DIR/cget.bash -h

to find out more about the HTTP conditional request client.

Installation

Download the source, change directory to the source directory, and install the source into /tmp as follows:

$ export BIN_DIR=/tmp/bin
$ export LIB_DIR=/tmp/lib
$ ./install.sh $BIN_DIR $LIB_DIR

or install into your home directory:

$ export BIN_DIR=$HOME/dev/bin
$ export LIB_DIR=$HOME/dev/lib
$ ./install.sh $BIN_DIR $LIB_DIR

A given target directory will be created if one doesn't already exist. The following commands confirm that the files were installed:

$ ls -1 $BIN_DIR | head -n 5
cget.bash
chead.bash
http_cache_check.bash
http_cache_diff.bash
http_cache_file.bash

$ ls -1 $LIB_DIR | head -n 5
compatible_date.bash
config_tools.bash
core_lib.bash
http_cache_tools.bash
http_log_tools.bash

Environment

Overall the scripts leverage the following environment variables (including BIN_DIR and LIB_DIR above):

Variable
BIN_DIR	A directory of executable scripts	REQUIRED
LIB_DIR	A directory of library source code	REQUIRED
CACHE_DIR	A persistent HTTP cache directory	REQUIRED
TMPDIR	A temporary directory	REQUIRED
LOG_FILE	A persistent log file	REQUIRED
LOG_LEVEL	The global log level [0..5]	OPTIONAL

All but LOG_LEVEL are REQUIRED. See the following section for more info about logging.

Note: Some OSes define TMPDIR and some do not. In any case, a temporary directory by that name is required to use these scripts.

Assuming your OS defines TMPDIR, the following environment variables will suffice:

export BIN_DIR=/tmp/bin
export LIB_DIR=/tmp/lib
export CACHE_DIR=/tmp/http_cache
export LOG_FILE=/tmp/bash_log.txt

Logging

Various log levels are supported:

	LOG_LEVEL
TRACE	5
DEBUG	4
INFO	3
WARN	2
ERROR	1
FATAL	0

The default log level is INFO (i.e., if you do not explicitly set the optional LOG_LEVEL environment variable, the value LOG_LEVEL=3 is assumed by default).

Note: Some of the scripts have command-line options that set the log level on-the-fly. See the script help file for details.

Compatibility

The shell scripts are compatible with both GNU/Linux and Mac OS.

Dependencies

None