4 ms·

I wanted to test Gemini's code generation so I asked it for a bash script iterating through an array of directory names and executing a command for each one. I

by thefz 1y ago

I wanted to test Gemini's code generation so I asked it for a bash script iterating through an array of directory names and executing a command for each one. It got it wrong. The command was generated outside of the for, and never updated inside the loop effectively making it useless. Luckily I know bash so I spotted it immediately. But I wonder how it's "removing programming language barriers" when one that does not know its output language can not spot even such a glaring issue.

jiggawatts 1y ago
I think this is more of a criticism of bash than of Gemini. Also, I out-of-hand reject any criticism of an AI that specifies only the brand ("ChatGPT") and not the specific model version, settings, etc... So, for example, Gemini 2.5 Pro (Jan 2025) with temperature 0.15 prompted with: "Write a short, idiomatic bash script that takes a file containing a list of directory names, changes to each one, runs a command, and then returns to the original working directory." Spits out this: #!/bin/bash # A script to run a command in a list of directories. # Exit if the wrong number of arguments are provided. if [[ $# -lt 2 ]]; then echo "Usage: $0 <file_with_dirs> <command> [args...]" >&2 exit 1 fi DIR_FILE="$1" shift # The rest of the arguments ("$@") are now the command. # Ensure the directory list file exists and is readable. if [[ ! -r "$DIR_FILE" ]]; then echo "Error: Cannot read file '$DIR_FILE'" >&2 exit 1 fi # Read the file line by line. while IFS= read -r dir; do # Skip empty lines or non-existent directories. if [[ -n "$dir" && -d "$dir" ]]; then echo "==> Entering '$dir'..." # Run command in a subshell to keep the 'cd' local. # '&&' ensures the command only runs if 'cd' succeeds. (cd "$dir" && "$@") echo "<== Finished with '$dir'." else echo "--> Skipping invalid directory: '$dir'" >&2 fi done < "$DIR_FILE" echo "All done." That worked for me, but I was testing it in WSL 2 where I got a gibberish error... which was because I edited the file in Windows Notepad and the line endings were confusing bash. Gemini helpfully told me how to fix that too! Something that I found amusing, and again, is a criticism of bash instead of the AI, is that this fails to process the last line if it isn't terminated with a \n character. PS: This is almost a one-liner in PowerShell, and works with or without the final terminator character: Push-Location Get-Content dirs.txt | cd -PassThru | Foreach-Object { echo "Hello from: $pwd" } Pop-Location Gemini also helped me code-golf this down to: pushd;gc dirs.txt|%{cd $_;"Hello from: $pwd"};popd
- oneshtein 1y ago
  for dir in $(cat dirs.txt); do ( cd "$dir"; echo "Hello from $(pwd)" ); done
  - lucianbr 1y ago
    Unbelievable how long and convoluted the other answer is, and that it is presented as proof that the AI provided a good solution.
    - jiggawatts 1y ago
      I asked for a "script". Asking for a one-liner does just that, with no input validation, comments, etc... Fundamentally, bash is just... verbose. I.e.: Here's the same task implemented in two scripting languages: PowerShell is 5 lines of code: https://learn.microsoft.com/en-us/azure/virtual-machines/enable-nvme-temp-faqs#azure-powershell-script https://learn.microsoft.com/en-us/azure/virtual-machines/ena... Bash is several pages: https://learn.microsoft.com/en-us/azure/virtual-machines/enable-nvme-temp-faqs#how-can-i-format-and-initialize-temp-nvme-disks-in-linux- https://learn.microsoft.com/en-us/azure/virtual-machines/ena...
      - skydhash 1y ago
        That's more of a reflection of the environment than the scripting language. On a mostly bare linux (debian netinstall or alpine), you are left with loads of text to parse. But as soon as that script becomes unwieldy, then the next option is write an actual program. Windows can afford to do that, because there's only few version out there. But there are lots of different Linux installations. And even the kernel is not guaranteed to be vanilla. So you're either write a script like this, or you go find programs that can help you out.
  - thefz 1y ago
    Out of curiosity isn't () spawning a subshell?
- thefz 1y ago
theshrike79 1y ago
That’s a bash problem, not LLM. I’ve done similar tools with Go and haven’t had any issues. One goes through a tree of dirs, finds zip files with images, unzips, benchmarks which image format is the most compact and creates a new zip with that. Got it right the first go (hehe pun)

by thefz 1y ago

jiggawatts 1y ago

I think this is more of a criticism of bash than of Gemini. Also, I out-of-hand reject any criticism of an AI that specifies only the brand ("ChatGPT") and not the specific model version, settings, etc... So, for example, Gemini 2.5 Pro (Jan 2025) with temperature 0.15 prompted with: "Write a short, idiomatic bash script that takes a file containing a list of directory names, changes to each one, runs a command, and then returns to the original working directory." Spits out this: #!/bin/bash # A script to run a command in a list of directories. # Exit if the wrong number of arguments are provided. if [[ $# -lt 2 ]]; then echo "Usage: $0 <file_with_dirs> <command> [args...]" >&2 exit 1 fi DIR_FILE="$1" shift # The rest of the arguments ("$@") are now the command. # Ensure the directory list file exists and is readable. if [[ ! -r "$DIR_FILE" ]]; then echo "Error: Cannot read file '$DIR_FILE'" >&2 exit 1 fi # Read the file line by line. while IFS= read -r dir; do # Skip empty lines or non-existent directories. if [[ -n "$dir" && -d "$dir" ]]; then echo "==> Entering '$dir'..." # Run command in a subshell to keep the 'cd' local. # '&&' ensures the command only runs if 'cd' succeeds. (cd "$dir" && "$@") echo "<== Finished with '$dir'." else echo "--> Skipping invalid directory: '$dir'" >&2 fi done < "$DIR_FILE" echo "All done." That worked for me, but I was testing it in WSL 2 where I got a gibberish error... which was because I edited the file in Windows Notepad and the line endings were confusing bash. Gemini helpfully told me how to fix that too! Something that I found amusing, and again, is a criticism of bash instead of the AI, is that this fails to process the last line if it isn't terminated with a \n character. PS: This is almost a one-liner in PowerShell, and works with or without the final terminator character: Push-Location Get-Content dirs.txt | cd -PassThru | Foreach-Object { echo "Hello from: $pwd" } Pop-Location Gemini also helped me code-golf this down to: pushd;gc dirs.txt|%{cd $_;"Hello from: $pwd"};popd

oneshtein 1y ago
for dir in $(cat dirs.txt); do ( cd "$dir"; echo "Hello from $(pwd)" ); done
- lucianbr 1y ago
  Unbelievable how long and convoluted the other answer is, and that it is presented as proof that the AI provided a good solution.
  - jiggawatts 1y ago
    I asked for a "script". Asking for a one-liner does just that, with no input validation, comments, etc... Fundamentally, bash is just... verbose. I.e.: Here's the same task implemented in two scripting languages: PowerShell is 5 lines of code: https://learn.microsoft.com/en-us/azure/virtual-machines/enable-nvme-temp-faqs#azure-powershell-script https://learn.microsoft.com/en-us/azure/virtual-machines/ena... Bash is several pages: https://learn.microsoft.com/en-us/azure/virtual-machines/enable-nvme-temp-faqs#how-can-i-format-and-initialize-temp-nvme-disks-in-linux- https://learn.microsoft.com/en-us/azure/virtual-machines/ena...
    - skydhash 1y ago
      That's more of a reflection of the environment than the scripting language. On a mostly bare linux (debian netinstall or alpine), you are left with loads of text to parse. But as soon as that script becomes unwieldy, then the next option is write an actual program. Windows can afford to do that, because there's only few version out there. But there are lots of different Linux installations. And even the kernel is not guaranteed to be vanilla. So you're either write a script like this, or you go find programs that can help you out.
- thefz 1y ago
  Out of curiosity isn't () spawning a subshell?
thefz 1y ago

theshrike79 1y ago

That’s a bash problem, not LLM. I’ve done similar tools with Go and haven’t had any issues. One goes through a tree of dirs, finds zip files with images, unzips, benchmarks which image format is the most compact and creates a new zip with that. Got it right the first go (hehe pun)