如何确定我正在使用的当前shell ?
仅仅ps命令的输出就足够了吗?
如何在不同风格的Unix中实现这一点?
如何确定我正在使用的当前shell ?
仅仅ps命令的输出就足够了吗?
如何在不同风格的Unix中实现这一点?
当前回答
在Mac OS X(和FreeBSD)上:
ps -p $$ -axco command | sed -n '$p'
其他回答
There are three approaches to finding the name of the current shell's executable: Please note that all three approaches can be fooled if the executable of the shell is /bin/sh, but it's really a renamed bash, for example (which frequently happens). Thus your second question of whether ps output will do is answered with "not always". echo $0 - will print the program name... which in the case of the shell is the actual shell. ps -ef | grep $$ | 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.
一种方法是:
ps -p $$ -o exe=
在我看来,这比在另一个答案中使用-o args或-o comm更好(这些可能会使用一些符号链接,例如当/bin/sh指向某个特定的shell,如Dash或Bash)。
上面返回的是可执行文件的路径,但要注意,由于/usr-merge,可能需要检查多个路径(例如/bin/bash和/usr/bin/bash)。
还要注意,上面的文件并不完全与POSIX兼容(POSIX ps没有exe)。
有许多方法可以找到shell及其对应的版本。下面是一些对我有用的方法。
直截了当的
$> echo $0(给你程序名。在我的例子中,输出是-bash。) $> $SHELL(这将带您进入SHELL,并在提示符中获得SHELL名称和版本。在我的情况下bash3.2$。) $> echo $SHELL(这将给你可执行的路径。在我的情况下/bin/bash。) $> $SHELL——version(这将提供有关许可证类型的SHELL软件的完整信息)
独创性的方法
$> *******(输入一组随机字符,在输出中您将获得shell名称。在我的例子中-bash: chapter2-a-sample-isomorphic-app: command not found)
我特别喜欢Nahuel Fouilleul的解决方案,但我不得不在Ubuntu 18.04 (Bionic Beaver)上使用内置的Bash shell运行它的以下变体:
bash -c 'shellPID=$$; ps -ocomm= -q $shellPID'
没有临时变量shellPID,例如:
bash -c 'ps -ocomm= -q $$'
只会输出ps。也许你们不是都在使用非交互模式,这是有区别的。
我想到了这个:
sed 's/.*SHELL=//; s/[[:upper:]].*//' /proc/$$/environ