有条件地在 bash 脚本中包含管道阶段

Question

我有一个如下所示的脚本：

flag=false
# Do a bunch of stuff that might set flag to true.
if [[ "$flag" == "true" ]]; then
   command \
       | pipe_command_a \
       | pipe_command_b \
       | pipe_command_c \
       | pipe_command_d \
       > "${output_path}"
else
   command \
       | pipe_command_a \
       | pipe_command_c \
       | pipe_command_d \
       > "${output_path}"
fi

flagbeingtrue或make之间的唯一区别false是pipe_command_b可能无法运行。有没有办法折叠它，这样我就不必重复所有常见的事情？

Answer 1

如果您想跳过它，请使用cat而不是命令：

command=cat
if [[ $flag == true ]] ; then
    command=pipe_command_b
fi
command \
    | pipe_command_a \
    | $command       \
    | pipe_command_c