bash 脚本：嵌套命令的结果未分配给变量

Question

Having string of pattern:st2-api-alpha

wanted to trim them like st2-api

Basically wanted to remove the text followed by 2nd occurence on '-' for each string.

Below are my statements:

    for (( i=1; i<${#all_containers_list[@]}; i++ )){
        echo "trimmed[$i] - "${all_containers_list[i]}|cut -f1-3 -d'-'
        temp="$(${all_containers_list[i]}| cut -f1-3 -d'-')"
        echo "temp is:$temp"

        all_containers_list[i]=$temp
        echo "all_containers_list[$i] is ${all_containers_list[i]}"
    }

when i echo:

trimmed[1] - st2-ui

/home/****/st2-monitoring/monitors/getAllContainerStatus_v1.1.sh: line 139: st2-ui-server-alpha: command not found

temp is:

all_containers_list[1] is

trimmed[2] - st2-api

/home/****/st2-monitoring/monitors/getAllContainerStatus_v1.1.sh: line 139: st2-api-alpha: command not found

temp is:

all_containers_list[2] is

trimmed[3] - st2-whiteboard

/home/****/st2-monitoring/monitors/getAllContainerStatus_v1.1.sh: line 139: st2-whiteboard-alpha: command not found

temp is:

all_containers_list[3] is

trimmed[4] - st2-aspose

/home/****/st2-monitoring/monitors/getAllContainerStatus_v1.1.sh: line 139: st2-aspose-alpha: command not found

temp is:

all_containers_list[4] is

trimmed[5] - determined_bassi

/home/****/st2-monitoring/monitors/getAllContainerStatus_v1.1.sh: line 139: determined_bassi: command not found

temp is:

all_containers_list[5] is

trimmed[6] - st2-ui

/home/ /st2-monitoring/monitors/getAllContainerStatus_v1.1.sh: line 139: st2-ui- -alpha: command not found

temp is:

all_containers_list[6] is

1. echo "trimmed[$i] - "${all_containers_list[i]}|cut -f1-3 -d'-' --- This is working fine.

2. But the below assignment is not working temp=$(${all_containers_list[i]}| cut -f1-3 -d'-')

Request your help to fix the same! OS is CentOS , bash script

Answer 1

I think calling subprocesses just for removing a part of a string, is a bit of an overkill. Assuming that you have stored your string in a variable, say

str=st2-api-alpha

you could simply do a

if [[ $str =~ [^-]*-[^-]* ]]
then
  str=${BASH_REMATCH[0]}
fi

If the string does not contain a dash, it is left unchanged. You can trvially generalize this solution to your case of having an array of strings.