Check if conda env exists and create if not in bash

user_12334353 0
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I have a build script to run a simple python app. I am trying to set it up that it will run for any user that has conda installed and in their PATH. No other prerequisites. I have that pretty much accomplished but would like to make it more efficient for returning users.

build_run.sh

conda init bash
conda env create --name RUN_ENV --file ../run_env.yml -q --force
conda activate RUN_ENV
python run_app.py
conda deactivate

I would like to make it that the script checks if RUN_ENV already exists and activates it instead of forcing its creation every time. I tried

ENVS=$(conda env list | awk '{print }' )
if [[ conda env list = *"RUN_ENV"* ]]; then
   conda activate RUN_ENV
else 
   conda env create --name RUN_ENV --file ../run_env.yml -q
   conda activate RUN_ENV
   exit
fi;
python run_app.py
conda deactivate

but it always came back as false and tried to create RUN_ENV

conda python bash
1 Answers

i am not sure how conda env list works (i don't use Anaconda); and your current if-tests are vague

but i'm going out on a limb and guessing this is what you're looking for

#!/usr/bin/env bash
# ...
find_in_conda_env(){
    conda env list | grep "${@}" >/dev/null 2>/dev/null
}

if find_in_conda_env ".*RUN_ENV.*" ; then
   conda activate RUN_ENV
else 
# ...

instead of bringing it out into a separate function, you could also do

# ...
if conda env list | grep ".*RUN_ENV.*" >/dev/null 2>&1; then
# ...

bonus points for neatness and clarity if you use command grouping

# ...
if { conda env list | grep 'RUN_ENV'; } >/dev/null 2>&1; then
# ...

if simply checks the exit code. and grep exits with 0 (success) as long as there's at least one match of the pattern provided; this evaluates to "true" in the if statement

(grep would match and succeed even if the pattern is just 'RUN_ENV' ;) )

the awk portion of ENVS=$(conda env list | awk '{print }' ) does virtually nothing. i would expect the output to be in tabular format, but {print } does no filtering, i believe you were looking for {print $n} where n is a column number or awk /PATTERN/ {print} where PATTERN is likely RUN_ENV and only lines which have PATTERN are printed.

but even so, storing a table in a string variable is going to be messing. you might want an array.

then coming to your if-condition, it's plain syntactically wrong.

  • the [[ construct is for comparing values: integer, string, regex
  • but here on the left of = we have a command conda env list
    • which i believe is also the contents of $ENVS
  • hence we can assume you meant [[ "${ENVS}" == *"RUN_ENV"* ]]
    • or alternately [[ $(conda env list) == *"RUN_ENV"* ]]
  • but still, regex matching against a table... not very intuitive imo
  • but it works... sort of
  • the proper clean syntax for regex matching is
    • [[ ${value} =~ /PATTERN/ ]]
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