Implementation

The Bash shell script that implements the PaLM shell as PaLMShell.bash is a script of approximately 100 lines of code in length. This short length demonstrates the simplicity of the PaLM shell in comparison to the compiled high-level language examples available.

Ignoring line comments, the length of the PaLM shell script is nearly halved to 40 lines of code. Thus half the Bash script source code is comments to document and explain the PaLM shell Bash script.

Initialize

The initialize section initializes, or sets up, the Bash script (Listing 1). The header with information about the Bash script is reported, including the release, version, and copyright.

01 PALM_KEY="NHGUBE-PBATENGF-BA-XABJVAT-EBG13-PBQVAT"
02
03 #
04 #
05 #
06 echo "PaLM Shell v1.1 (c) 2023 William F. Gilreath"
07 echo "All Rights Reserved. License is GPLv3       "
08 echo
09
10 #
11 # check if PALM_KEY empty, report error need key, exit
12 if [ -z $PALM_KEY ]
13 then
14   echo "Must have PaLM key to use PaLM API!"
15   exit 1
16 fi
17
18 date_time=$(date | date | tr '  ' '-' | tr ':' '-')
19 log_file="PaLM-$date_time.log"
20
21 echo
22 echo "Logging this session to: 'PaLM-$date_time.log'"
23 echo

The script then checks that the variable PALM_KEY, which is the RESTful API key provided by Google to access the Pathways LLM, exists and is set. If not, the script exits, as it cannot access the RESTful API.

Then the date and time are used to create the transcript or log filename used by the script; the filename generated is then reported to the user.

Main Body Infinite Loop

The main body of the bash script for the PaLM shell is an infinite loop (Listing 2). The infinite loop is the software classic REPL. A while loop continues the process of evaluating prompts (see the "Prompt Engineering" box for more on prompts). The command-line prompt is printed, and then the user prompt line read.

01 while :
02 do
03   echo -n "PaLM>"
04   read prompt_line
05
06   #'bye' is bye/exit/quit PaLM Shell
07   if [ "$prompt_line" == "bye" ]; then
08     break
09   fi
10
11   echo "Prompt: '$prompt_line'" | tee -a $log_file
12
13   echo | tee -a $log_file #PaLM-$date_time.log
14
15   curl \
16   -s \
17   -H 'Content-Type: application/json' \
18   -d '{ "prompt": { "text": '"\"$prompt_line\""' }}' \
19  "https://generativelanguage.googleapis.com/v1beta2/models/text-bison-001:
20 generateText?key=$PALM_KEY" |  jq '.candidates | .[].output' | sed 's/\\n/\n/g'
21 | tee -a $log_file #PaLM-$date_time.log
22
23   echo | tee -a $log_file ##PaLM-$date_time.log
24
25 done

If the input is only the command bye, the while loop is broken to continue the rest of the script. Otherwise the input is a prompt, in which case that prompt is reported and then sent to the Pathways LLM via a RESTful HTTP call. The response is received and then printed to the user. All the output to the user is also recorded as a transcript to the log file.