Question

好的，所以有些奇怪似乎正在发生。当我以交互方式运行history -r时，它按预期工作：

$ printf %b '#1401928364\necho\n' > /tmp/hist  # Make a test history file with timestamp information.
$ history -r /tmp/hist  # Read it into the current history.
$ history 3  # Bash has interpreted the history comment character such that timestamps don't appear on their own line.
  220  2014-06-05Thu17:59:55  history -r /tmp/hist  # Read it into the current history.
  221  2014-06-05Thu00:32:44  echo
  222  2014-06-05Thu18:00:07  history 3  # Bash has interpreted the history comment character such that timestamps don't appear on their own line.

但是，从我的.bashrc运行它并不具有相同的预期行为：

$ printf %b 'history -r /tmp/hist\nhistory 3\n' > /tmp/bashrc  # Make a test bashrc file.
$ bash --rcfile /tmp/bashrc  # Run Bash with the test bashrc file; doesn't interpret the history comment character and prints a line containing ‘#1401928364’.
    1  #1401928364
    2  echo

我可以通过Freenode上的 shbot 确认：

17:29:45 <JamesJRH> # printf %b '#1401928364\necho\n' > /tmp/hist; history -r /tmp/hist; history 3
17:29:47 <shbot>     1  printf %b '#1401928364\necho\n' > /tmp/hist; history -r /tmp/hist; history 3
17:29:47 <shbot>     2  echo
17:29:49 <JamesJRH> # printf %b '#1401928364\necho\n' > /tmp/hist; printf %b 'history -r /tmp/hist\nhistory 3\n' > /tmp/bashrc; bash --rcfile /tmp/bashrc
17:29:55 <shbot>     1  #1401928364
17:29:55 <shbot>     2  echo

那么这里发生了什么？如何从.bashrc文件中正常使用它？

更新

用我的shell：

$ echo "$BASH_VERSION"; printf %b '#1401928364\necho\n' > /tmp/hist; printf %b 'export HISTTIMEFORMAT=\x27%F%a%T  \x27\nhistory -r /tmp/hist\nhistory 3\n' > /tmp/bashrc; bash --rcfile /tmp/bashrc
4.2.45(1)-release
    1  2014-06-05Thu19:42:31  #1401928364
    2  2014-06-05Thu19:42:31  echo

Summary                 interactive  bashrc
without HISTTIMEFORMAT  Succeeds.    Fails.
with HISTTIMEFORMAT     Succeeds.    Fails.

使用 shbot ：

19:45:29 <JamesJRH> # echo "$BASH_VERSION"; printf %b '#1401928364\necho\n' > /tmp/hist; printf %b 'export HISTTIMEFORMAT=\x27%F%a%T  \x27\nhistory -r /tmp/hist\nhistory 3\n' > /tmp/bashrc; bash --rcfile /tmp/bashrc
19:45:36 <shbot> 4.3.18(1)-release
19:45:36 <shbot>     1  2014-06-05Thu00:32:44  echo
19:45:49 <JamesJRH> 42# echo "$BASH_VERSION"; printf %b '#1401928364\necho\n' > /tmp/hist; printf %b 'export HISTTIMEFORMAT=\x27%F%a%T  \x27\nhistory -r /tmp/hist\nhistory 3\n' > /tmp/bashrc; bash --rcfile /tmp/bashrc
19:45:56 <shbot> 4.2.47(2)-release
19:45:56 <shbot>     1  2014-06-05Thu00:32:44  echo
19:46:08 <JamesJRH> 41# echo "$BASH_VERSION"; printf %b '#1401928364\necho\n' > /tmp/hist; printf %b 'export HISTTIMEFORMAT=\x27%F%a%T  \x27\nhistory -r /tmp/hist\nhistory 3\n' > /tmp/bashrc; bash --rcfile /tmp/bashrc
19:46:15 <shbot> 4.1.11(1)-release
19:46:15 <shbot>     1  2014-06-05Thu00:32:44  echo

Summary                 interactive  bashrc
without HISTTIMEFORMAT  Succeeds.    Fails.
with HISTTIMEFORMAT     Succeeds.    Succeeds.

那么我的Bash和 shbot 之间可能造成什么差异呢？

Answer 1

如果设置HISTTIMEFORMAT env，它是否有效。首先变量，然后再尝试运行历史记录？

export HISTTIMEFORMAT="%F %T "

如果未设置HISTTIMEFORMAT，则时间戳不会写入历史记录文件中。

Answer 2

唉!!

我终于确定了我的shell和 shbot 之间的区别，而且确实是我第一次怀疑的Bash 版本，但 shbot 通过我向我撒谎！好吧，实际上它是由于 shbot 的实现细节，但我的命令的这种变化给出了哪些版本工作与否的真实故事：

03:31:11 <JamesJRH> # printf %b '#1401928364\necho\n' > /tmp/hist; printf %b 'echo "$BASH_VERSION"\nexport HISTTIMEFORMAT=\x27%F%a%T  \x27\nhistory -r /tmp/hist\nhistory 3\n' > /tmp/bashrc; bash --rcfile /tmp/bashrc
03:31:18 <shbot> 4.3.18(1)-release
03:31:18 <shbot>     1  2014-06-05Thu00:32:44  echo
03:31:25 <JamesJRH> # printf %b '#1401928364\necho\n' > /tmp/hist; printf %b 'echo "$BASH_VERSION"\nexport HISTTIMEFORMAT=\x27%F%a%T  \x27\nhistory -r /tmp/hist\nhistory 3\n' > /tmp/bashrc; bash42 --rcfile /tmp/bashrc
03:31:32 <shbot> 4.2.47(2)-release
03:31:32 <shbot>     1  2014-06-06Fri03:31:24  #1401928364
03:31:32 <shbot>     2  2014-06-06Fri03:31:24  echo

所以现在摘要是指版本！

使用Bash 4.2及更早版本：

Summary                 interactive  bashrc
without HISTTIMEFORMAT  Succeeds.    Fails.
with HISTTIMEFORMAT     Succeeds.    Fails.*

*测试4.2.47（2）-release，4.2.45（1）-release，4.2.25（1）-release，4.2.8（1）-release，4.1.11（1 ）-release，4.0.38（1）-release，3.2.51（2）-release，3.2.39（1）-release。

从Bash 4.3开始：

Summary                 interactive  bashrc
without HISTTIMEFORMAT  Succeeds.    Fails.
with HISTTIMEFORMAT     Succeeds.    Succeeds.*

*测试4.3.18（1） - 发布。

仍然不完全确定为什么HISTTIMEFORMAT不需要交互式，但需要.bashrc，但这不是问题。

所以问题的直接答案是：如果使用的Bash版本至少为4.3并且.bashrc变量设置且不为null，则仅从HISTTIMEFORMAT解释它们。在我的情况下HISTTIMEFORMAT已经在我的.bashrc中设置，因此问题就是版本。显然这是一个错误，这个错误已得到修复。

刚才需要去安装Bash 4.3 ......： - ）

如果我从.bashrc运行`history -r`，为什么不解释时间戳？

2 个答案: