[英]shorthand for creating empty file in bash not working properly in zsh
In bash, an empty file can be created with:在 bash 中,可以使用以下命令创建一个空文件:
> empty_file.txt
In zsh, the same command gets stuck and needs to be stopped.在 zsh 中,同样的命令卡住了,需要停止。 The file gets created nonetheless.
尽管如此,文件还是会被创建。
I would like to know what is causing this behaviour and/or how to make it similar to bash?我想知道是什么导致了这种行为和/或如何使它类似于 bash?
Edit: typo.编辑:错别字。
If you don't specify a command for your redirection, then Bash will behave (accordingly to POSIX) as if the command was true
.如果您没有为重定向指定命令,那么 Bash 的行为(根据 POSIX)就好像该命令为
true
。 By default, unless in compatibility mode, zsh
will instead behave as if the command was cat
.默认情况下,除非在兼容模式下,否则
zsh
行为就像命令是cat
。
You can simply explicitly specify the command true
(or its harder-to-read alias :
) to make both shells behave the same:您可以简单地明确指定命令
true
(或其难以阅读的别名:
)以使两个 shell 的行为相同:
: > empty_file.txt
Here's man zsh
explaining the behavior and the options you can use to tweak it:这是
man zsh
解释行为和您可以用来调整它的选项:
REDIRECTIONS WITH NO COMMAND
When a simple command consists of one or more redirection operators
and zero or more parameter assignments, but no command name, zsh
can behave in several ways.
If the parameter NULLCMD is not set or the option CSH_NULLCMD is
set, an error is caused. This is the csh behavior and CSH_NULLCMD
is set by default when emulating csh.
If the option SH_NULLCMD is set, the builtin `:' is inserted as a
command with the given redirections. This is the default when emu‐
lating sh or ksh.
Otherwise, if the parameter NULLCMD is set, its value will be used
as a command with the given redirections. If both NULLCMD and
READNULLCMD are set, then the value of the latter will be used in‐
stead of that of the former when the redirection is an input. The
default for NULLCMD is `cat' and for READNULLCMD is `more'. Thus
< file
shows the contents of file on standard output, with paging if that
is a terminal. NULLCMD and READNULLCMD may refer to shell func‐
tions.
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