shlog.sh

#!/bin/bash
#
### Shell script logger
#
# Requires: tee
#
### To be sourced from other scripts
#
# Defines and uses the following variables globally: LOGDIR, LOGFILE, LOGPATH
# These variables can be set by parent script or can be defined with the shlog_vars function
#
### Can change this variable to set a default global directory. Can still be overridden by the global variables
globalLogDir="/var/log/scripts/"

shlog_check_dir ()
{
# Check if dir doesnt exist and try to create it. Check if it exists and that it is a directory and writable
if [[ ! -e "$1" ]]; then
  mkdir -p "$1" 2>/dev/null
  if [[ $? -ne 0 ]]; then
    echo "ERROR! - shlogDir ($1) does not exist and can not be created. Exiting..."
    exit 1
  fi
elif [[ ! -d "$1" ]]; then
  echo "ERROR! - shlogDir ($1) exists but is not a directory. Exiting..."
  exit 1
elif [[ ! -w "$1" ]]; then
  echo "ERROR! - shlogDir ($1) exists but is not writable. Exiting..."
  exit 1
fi
}

shlog_check_path ()
{
# Try to create the file or if it exists, check it it is writable
if [[ ! -e "$1" ]]; then
  touch "$1" 2>/dev/null
  if [[ $? -ne 0 ]]; then
    # Check if we have access to the dir or if we can create it
    shlog_check_dir "$(echo "$1" | grep -Eo '\/([^/]+\/)+')"
    # If we are still here, try to create it again
    touch "$1" 2>/dev/null
    if [[ $? -ne 0 ]]; then
      echo "ERROR! - shlogPath ($1) does not exist and can not be created. Exiting..."
      exit 1
    fi
  fi
elif [[ ! -w "$1" ]]; then
        echo "ERROR! - shlogPath ($1) exists but is not writable. Exiting..."
        exit 1
fi
}

shlog_validate_dir ()
{
# Check if dir has a leading slash and add it if it doesnt
if [[ ! "$1" =~ /$ ]]; then
  shlogDir="$1"/
else
  shlogDir="$1"
fi
}

shlog_logdir ()
{
# If LOGDIR has not been set by the parent script, check if the globalLogDir has been set in this script. If neither applies, set shlogDir based on the script dir
if [[ -z "$LOGDIR" ]]; then
  if [[ -z "$globalLogDir" ]]; then
    local relativeLogDir=$(dirname "$0")
    shlogDir=$(cd "$relativeLogDir" && pwd)
  else
    shlogDir="$globalLogDir"
  fi
else
  shlogDir="$LOGDIR"
fi
}

shlog_logfile ()
{
# If LOGFILE has not been set by the parent script, get its name, filter the path and replace extension with .log, if it has one
if [[ -z "$LOGFILE" ]]; then
  if [[ "$0" =~ \.sh ]]; then
    shlogFile=$(echo "$0" | sed 's/.*\///' | sed 's/sh$/log/')
  else
    shlogFile=$(echo "$0" | sed 's/.*\///').log
  fi
else
  shlogFile="$LOGFILE"
fi
}

shlog_vars ()
{
# -p flag set
if [[ -n "$shlogTmpPath" ]]; then
  # nolog option
  if [[ "$shlogTmpPath" == "nolog" ]]; then
    shlogPath="/dev/null"

  # Input is the full path
  elif [[ "$shlogTmpPath" =~ \/([^/]+\/)+[^/]+\.[^/]{1,3} ]]; then
    shlogPath="$shlogTmpPath"

  # Input is a dir, append default filename
  elif [[ "$shlogTmpPath" =~ \/([^/]+\/)+ ]]; then
    # Validate and populate shlogDir
    shlog_validate_dir "$shlogTmpPath"
    # Populate shlogFile
    shlog_logfile
    shlogPath="$shlogDir$shlogFile"

  # Input is a filename, append default dir
  elif [[ "$shlogTmpPath" =~ [^/]+\.[^/]{1,3} ]]; then
    # Populate shlogDir
    shlog_logdir
    shlog_validate_dir "$shlogDir"
    shlogPath="$shlogDir$shlogTmpPath"
  fi
  # Unset var to avoid running unnecessary tests when -p flag was not set
  unset shlogTmpPath

# LOGPATH not defined, build it based on LOGDIR and LOGFILE
elif [[ -z "$LOGPATH" ]]; then
  # Get shlogDir and shlogFile
  shlog_logdir
  shlog_validate_dir "$shlogDir"
  shlog_logfile
  shlogPath="$shlogDir$shlogFile"

# LOGPATH is set
else
  shlogPath="$LOGPATH"
fi

# Validate shlogPath
shlog_check_path "$shlogPath"
}

shlog_global_vars ()
{
case "$1" in
  -s|--set)
                shlog_vars
                LOGDIR="$shlogDir"
                LOGFILE="$shlogFile"
                LOGPATH="$shlogPath"
  ;;
        -u|--unset)
                LOGDIR=""
                LOGFILE=""
                LOGPATH=""
  ;;
esac
}

shlog_help ()
{
# Check if no arguments were given and print usage message
if [[ $# -eq 0 ]]; then
  echo "Usage: shlog [-p|--path=nolog|/alternative/path/alternative.log] [-s|--stamp=timestamp|datestamp|weekstamp] \"text\"|\"\$(cmd)\""
  exit 1
fi
}


### Main
shlog ()
{
# Put the arguments in variables
while [[ $# -gt 0 ]]; do
case "$1" in
  -s|--stamp)
    local shlogTmpStamp="$2"
    shift 2
  ;;
  -p|--path)
    local shlogTmpPath="$2"
    shift 2
  ;;
  *)
    local shlogTmpText="$1"
    shift
  ;;
esac
done

# Set shlogPath variable
shlog_vars

# Do the thing
if [[ -n $shlogTmpText ]]; then
  if [[ $shlogTmpStamp == "timestamp" ]]; then
    echo -e "$(date '+%H:%M:%S')" - "$shlogTmpText" | tee -a "$shlogPath"
  elif [[ $shlogTmpStamp == "datestamp" ]]; then
    echo -e "$(date '+%Y-%m-%d %H:%M:%S')" - "$shlogTmpText" | tee -a "$shlogPath"
  elif [[ $shlogTmpStamp == "weekstamp" ]]; then
    echo -e "$(date '+%H:%M:%S %d-%m-%Y %a %V')" - "$shlogTmpText" | tee -a "$shlogPath"
  else
    echo -e "$shlogTmpText" | tee -a "$shlogPath"
  fi
else
  if [[ $shlogTmpStamp == "timestamp" ]]; then
    echo -e "$(date '+%H:%M:%S')" | tee -a "$shlogPath"
  elif [[ $shlogTmpStamp == "datestamp" ]]; then
    echo -e "$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "$shlogPath"
  elif [[ $shlogTmpStamp == "weekstamp" ]]; then
    echo -e "$(date '+%H:%M:%S %d-%m-%Y %a %V')" | tee -a "$shlogPath"
  fi
fi

unset shlogPath
unset shlogDir
unset shlogFile
}


### Throw warning if run from a shell
if [[ $0 =~ .*shlog ]]; then
  echo "This script can only executed as a source from within another script!"
  echo "To source it just add an entry in the script like: '. /path/to/shlog.sh'"
  echo ""
  shlog_help
fi