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我怎样才能在tcsh中达到这种效果？

tag-icon • tag-icon tcsh
我怎样才能在tcsh中达到这种效果？

在bash中，当我通过实现precmd()功能时trap ??? DEBUG，如果precmd()调用中的命令返回非零返回代码，我可以使键入的命令无法执行；通过使用set -o functrace和shopt -s extdebug.

我正在尝试通过 tcshpostcmd中的别名在 tcsh 中实现类似的功能。但是，我无法在 tcsh 文档中找到有关如何执行与 bash 相同的操作的任何详细信息（如果命令postcmd失败并返回非零 RC，则不要执行在提示符下键入的命令）。

我怎样才能在tcsh中达到这种效果？

期望的结果：

# Set up postcmd alias to check of current user is "OK" (in OK file)
MYUSER:~> alias postcmd 'grep $USER /tmp/ok_users > /dev/null'

# Add myself to OK list  (in another xterm)
MYUSER:~> echo "$USER" > ! /tmp/ok_users
MYUSER:~> cat /tmp/ok_users
MYUSER

MYUSER:~> grep $USER /tmp/ok_users | wc -l; echo $?
1
0

# Run command - expect it to succeed:
MYUSER:~> echo TEST2
TEST2  # <==== As expected

##########
# Now, let's make sure I'm NOT in OK users (in another xterm).

MYUSER:~> echo "junk" > ! /tmp/ok_users
MYUSER:~> cat /tmp/ok_users
junk
MYUSER:~>  grep $USER /tmp/ok_users | wc -l ; echo $?
0
1

# Now, what I need is, for my typed command to NOT be executed
#     due to "postcmd" hook command (grep) failing

MYUSER:~> echo TEST2
MYUSER:~> <==== Want to NOT echo anything. How do I do that?

我希望答案是操作系统可移植的，但如果需要，至少它必须在 RedHat Enterprise Linux 6 上运行

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