logging.sh

###############################################################################
#
# Bash helper functions for logging.
#
# Inspired in Python logging.  Ready to source it in your bash script.
# It can redirect all the output to a file and also redirect all the
# trace to another file, which is useful for debugging.
#
# Usage: see how to use it in the test at the bottom.
#
###############################################################################

# This is free and unencumbered software released into the public domain.

# Anyone is free to copy, modify, publish, use, compile, sell, or
# distribute this software, either in source code form or as a compiled
# binary, for any purpose, commercial or non-commercial, and by any
# means.

# In jurisdictions that recognize copyright laws, the author or authors
# of this software dedicate any and all copyright interest in the
# software to the public domain. We make this dedication for the benefit
# of the public at large and to the detriment of our heirs and
# successors. We intend this dedication to be an overt act of
# relinquishment in perpetuity of all present and future rights to this
# software under copyright law.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.

setup_loglevel() {
    case $1 in
        debug)
            export RL_LOG_LEVEL=1 ;;
        info)
            export RL_LOG_LEVEL=2 ;;
        warning)
            export RL_LOG_LEVEL=3 ;;
        error)
            export RL_LOG_LEVEL=4 ;;
    esac
}
export RL_LOG_LEVEL=2

setup_logfile() {
    exec >  >(tee -a $1)
    exec 2> >(tee -a $1 >&2)
    log_debug "Logging to $1"
}

setup_logtrace() {
    exec 199>>$1
    export BASH_XTRACEFD=199
    set -x
    log_debug "Writting bash trace to $1"
}

log_debug() {
    if [ "$RL_LOG_LEVEL" -le "1" ]; then
        echo -e "`date +%s`\tDEBUG\t$1"
    fi
}

log_info() {
    if [ "$RL_LOG_LEVEL" -le "2" ]; then
        echo -e "`date +%s`\tINFO\t$1"
    fi
}

log_warning() {
    if [ "$RL_LOG_LEVEL" -le "3" ]; then
        echo -e "`date +%s`\tWARNING\t$1"
    fi
}

log_error() {
    if [ "$RL_LOG_LEVEL" -le "4" ]; then
        echo -e "`date +%s`\tERROR\t$1" >&2
    fi
}

test() {
    setup_loglevel "debug"
    setup_logfile "./test.log"
    setup_logtrace "./test.trace"

    log_info "Hello Ripley"
    log_warning "Xenomorph detected in area 32"
    log_info "All doors locked"
    log_error "Engines malfunctioning"
    log_debug "Energy 12%"
    log_debug "Energy 4%"
    log_info "System shutdown in 3... 2... 1..."
}
# test