Bash - 检查给定参数是否存在

Question

I have a separate shell script that runs my docker-compose environment in attached mode or detached if I pass -d or --detach argument. It works fine when I pass this argument ( ./run-env.sh -d ) but it doesn't when I run my script without any option ( ./run-env , just getting blank output and docker-compose doesn't run), where can be a problem?

#!/usr/bin/env bash

for arg in "$@"; do
    if [ "$arg" = '-d'  ] || [ "$arg" = '--detach'  ]
    then
         docker-compose  -f docker-compose.local-environment.yml up --build -V --detach
    else
         docker-compose  -f docker-compose.local-environment.yml up --build -V --abort-on-container-exit
    fi
done

Answer 1

When you don't give argument, you don't even enter the for loop, that's why nothing happens.

#!/usr/bin/env bash

# By default, use '--abort-on-container-exit' option
abort_or_detach="--abort-on-container-exit"

# Search for a parameter asking to run in detached mode
for arg in "$@"; do
    if [ "$arg" = '-d'  ] || [ "$arg" = '--detach'  ]
    then
         abort_or_detach="--detach"
    fi
done

# Run with the correct option
docker-compose -f docker-compose.local-environment.yml up --build -V $abort_or_detach

Here in this script, you call one time docker-compose , and you can manage easily the options with the for loop

Also, with your first try, you would launch docker-compose as many times as you have different parameters. Here, you treat them, and then do a single launch

Answer 2

for arg in "$@" iterates over the arguments. When you pass no arguments, it iterates zero times. Instead, try something like:

extra=--abort-on-container-exit
for arg; do
    case "$arg" in
    -d|--detach) extra=--detach
    esac
done

docker-compose  -f docker-compose.local-environment.yml up --build -V $extra

Note that this is one of those cases where you do not want to put quotes around $extra , because if extra is the empty string you don't want to pass anything to docker-compose. (Here, the default will ensure it is not empty, but this is a fairly common pattern and there are cases where it will be the empty string.)