不需要从"ps"的输出中Grepping PID，因为你可以从/proc目录结构中读取任何PID的相应命令行:

echo $(cat /proc/$$/cmdline)

然而，这可能并不比简单地:

echo $0

关于运行一个与名称不同的shell，一个想法是使用之前获得的名称从shell请求版本:

<some_shell> --version

sh似乎失败的退出码2，而其他人给出一些有用的(但我无法验证所有，因为我没有他们):

$ sh --version
sh: 0: Illegal option --
echo $?
2

我有一个简单的技巧来找到当前的壳。只需输入一个随机字符串(这不是命令)。它将失败并返回一个“not found”错误，但在行开始时，它会说它是哪个shell:

ksh: aaaaa: not found [No such file or directory]
bash: aaaaa: command not found

There are three approaches to finding the name of the current shell's executable: Please note that all three approaches can be fooled if the executable of the shell is /bin/sh, but it's really a renamed bash, for example (which frequently happens). Thus your second question of whether ps output will do is answered with "not always". echo $0 - will print the program name... which in the case of the shell is the actual shell. ps -ef | grep $$ | grep -v grep - this will look for the current process ID in the list of running processes. Since the current process is the shell, it will be included. This is not 100% reliable, as you might have other processes whose ps listing includes the same number as shell's process ID, especially if that ID is a small number (for example, if the shell's PID is "5", you may find processes called "java5" or "perl5" in the same grep output!). This is the second problem with the "ps" approach, on top of not being able to rely on the shell name. echo $SHELL - The path to the current shell is stored as the SHELL variable for any shell. The caveat for this one is that if you launch a shell explicitly as a subprocess (for example, it's not your login shell), you will get your login shell's value instead. If that's a possibility, use the ps or $0 approach. If, however, the executable doesn't match your actual shell (e.g. /bin/sh is actually bash or ksh), you need heuristics. Here are some environmental variables specific to various shells: $version is set on tcsh $BASH is set on bash $shell (lowercase) is set to actual shell name in csh or tcsh $ZSH_NAME is set on zsh ksh has $PS3 and $PS4 set, whereas the normal Bourne shell (sh) only has $PS1 and $PS2 set. This generally seems like the hardest to distinguish - the only difference in the entire set of environment variables between sh and ksh we have installed on Solaris boxen is $ERRNO, $FCEDIT, $LINENO, $PPID, $PS3, $PS4, $RANDOM, $SECONDS, and $TMOUT.

echo $$ # Gives the Parent Process ID 
ps -ef | grep $$ | awk '{print $8}' # Use the PID to see what the process is.

你如何知道你当前的shell是什么?

如果您只是想检查您正在运行(特定版本的)Bash，最好的方法是使用$BASH_VERSINFO数组变量。作为一个(只读)数组变量，它不能在环境中设置， 因此，您可以确定它来自当前shell(如果有的话)。

但是，由于Bash在作为sh调用时具有不同的行为，因此还需要检查以/ Bash结尾的$ Bash环境变量。

在我写的一个脚本中，使用了带-(不是下划线)的函数名，并依赖于关联数组(在Bash 4中添加)，我有以下完整性检查(有有用的用户错误消息):

case `eval 'echo $BASH@${BASH_VERSINFO[0]}' 2>/dev/null` in
    */bash@[456789])
        # Claims bash version 4+, check for func-names and associative arrays
        if ! eval "declare -A _ARRAY && func-name() { :; }" 2>/dev/null; then
            echo >&2 "bash $BASH_VERSION is not supported (not really bash?)"
            exit 1
        fi
        ;;
    */bash@[123])
        echo >&2 "bash $BASH_VERSION is not supported (version 4+ required)"
        exit 1
        ;;
    *)
        echo >&2 "This script requires BASH (version 4+) - not regular sh"
        echo >&2 "Re-run as \"bash $CMD\" for proper operation"
        exit 1
        ;;
esac

在第一种情况下，您可以忽略对特性的功能检查，只假设将来的Bash版本是兼容的。

我特别喜欢Nahuel Fouilleul的解决方案，但我不得不在Ubuntu 18.04 (Bionic Beaver)上使用内置的Bash shell运行它的以下变体:

bash -c 'shellPID=$$; ps -ocomm= -q $shellPID'

没有临时变量shellPID，例如:

bash -c 'ps -ocomm= -q $$'

只会输出ps。也许你们不是都在使用非交互模式，这是有区别的。