Question

我有一个脚本，它使用当前流行的方法安装一些下载bash脚本并将其传输到shell中的软件包：

curl --silent https://sdk.cloud.google.com | bash

我想将上述命令生成的所有输出抑制为stdout。我尝试了显而易见的事实：

curl --silent https://sdk.cloud.google.com | bash > /dev/null

但是，下载脚本中的命令生成的输出仍然会回显给终端。我需要在这里使用稍微不同的语法吗？

Answer 1

阅读讨论，我建议进行一定程度的验证，特别是如果这是持续集成系统的一部分。在这种情况下你需要的最后一个是误报。我建议使用我编译的脚本来捕获stderr，stdout和返回代码，以便测试正确完成或记录输出以进一步诊断。我已将其包含在下面供您参考：

# #!/bin/bash
# 
# based on posts from stackexchange:
# http://stackoverflow.com/a/26827443/171475
# http://stackoverflow.com/a/18086548/171475
# http://stackoverflow.com/a/28796214/171475

function example_function {
    printf 'example output to stdout %d\n' {1..10}
    echo >&2 'example output to stderr'
    return 42
}



##############################
### using the dot operator ###

if [ "${BASH_VERSINFO}" -lt 4 ]; then
    printf '%s\n' "The source version of this script requires Bash v4 or higher."
else

    # stdout & stderr only
    source <({ cmd_err=$({ mapfile -t cmd_out < <(example_function); } 2>&1; declare -p cmd_out >&2); declare   -p cmd_err; } 2>&1)

    printf "\n%s\n" "SOURCE VERSION : STDOUT & STDERR ONLY"
    printf "%s\n" "${cmd_out[@]}"
    printf "%s\n" "${cmd_err}"

    unset cmd_out
    unset cmd_err


    # stdout & stderr only as well as return code:
    source <({ cmd_err=$({ mapfile -t cmd_out< <( \
        example_function \
      ; cmd_rtn=$?; declare -p cmd_rtn >&3); } 3>&2 2>&1; declare -p cmd_out >&2); declare -p cmd_err; } 2>&1)


    printf "\n%s\n" "SOURCE VERSION : STDOUT, STDERR & RETURN CODE"
    printf '%s\n' "${cmd_out[@]}"
    # alternative version
    # declare -p cmd_out 
    printf '%s\n' "${cmd_err}"
    printf '%s\n' "${cmd_rtn}"

    unset cmd_out
    unset cmd_err
    unset cmd_rtn

fi

##############################
######### using exec #########

# stdout & stderr only
eval "$({ cmd_err=$({ cmd_out=$( \
    example_function \
  ); } 2>&1; declare -p cmd_out >&2); declare -p cmd_err; } 2>&1)"

printf "\n%s\n" "EVAL VERSION : STDOUT & STDERR ONLY"
printf '%s\n' "${cmd_out}"
printf '%s\n' "${cmd_err}"
printf '%s\n' "${cmd_rtn}"

unset cmd_out
unset cmd_err

# stdout & stderr only as well as return code:
eval "$({ cmd_err=$({ cmd_out=$( \
    example_function \
  ); cmd_rtn=$?; } 2>&1; declare -p cmd_out cmd_rtn >&2); declare -p cmd_err; } 2>&1)"


printf "\n%s\n" "EVAL VERSION : STDOUT, STDERR & RETURN CODE"
printf '%s\n' "${cmd_out}"
printf '%s\n' "${cmd_err}"
printf '%s\n' "${cmd_rtn}"


unset cmd_out
unset cmd_err
unset cmd_rtn

应用于您的特定场景，它可能类似于：

source <({ cmd_err=$({ mapfile -t cmd_out< <( \
    curl --silent https://sdk.cloud.google.com | bash \
  ; cmd_rtn=$?; declare -p cmd_rtn >&3); } 3>&2 2>&1; declare -p cmd_out >&2); declare -p cmd_err; } 2>&1)

# return code 0 indicates the command executed fully
if [ "${cmd_rtn}" -eq "0" ]; then
    # the command succeeded
    printf 'The command succeeded\n' 

    # might should do some additional checking of the contents of
    # cmd_out or cmd_err for expected results

elsethen
    # the command failed, do some checking
    printf 'The command failed\n'

    # might should do some logging of the output for further reference
    # or fail the integration check
fi

printf '\n%s\n\n' "Example output of STDOUT, STDERR & RETURN CODE"
printf 'STDOUT: %s\n\n' "${cmd_out[@]}"
printf 'STDERR: %s\n\n' "${cmd_err}"
printf 'RETURN CODE: %s\n\n' "${cmd_rtn}"

如何将脚本传入bash并使其输出静音？

1 个答案: