Linux 强制 shell 脚本 fflush
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Force a shell script to fflush
提问by Tim Post
I was wondering if it was possible to tell bash that all calls to echoor printfshould be followed up by a subsequent call to fflush()on stdout/stderr respectively?
我想知道是否有可能告诉 bash对 stdout/stderr 的所有调用echo或printf应该随后分别调用fflush()stdout/stderr？
A quick and dirty solution would be to write my own printf implementation that did this and use it in lieu of either built in, but it occurred to me that I might not need to.
一个快速而肮脏的解决方案是编写我自己的 printf 实现来执行此操作并使用它代替内置的任何一个，但我突然想到我可能不需要这样做。
I'm writing several build scripts that run at once, for debugging needs I reallyneed to see messages that they write in order.
我正在编写几个同时运行的构建脚本，为了调试需求，我真的需要查看它们按顺序编写的消息。
采纳答案by pixelbeat
If comands use stdio and are connected to a terminal they'll be flushed per line. Otherwise you'll need to use something like stdbuf on commands in a pipe line http://www.pixelbeat.org/programming/stdio_buffering/
如果命令使用 stdio 并连接到终端，则每行都会刷新它们。否则，您将需要对管道中的命令使用 stdbuf 之类的东西 http://www.pixelbeat.org/programming/stdio_buffering/
tl;dr: instead of printf ...try to put to the script stdbuf -o0 printf .., or stdbuf -oL printf ...
tl;dr: 而不是printf ...尝试放入脚本stdbuf -o0 printf ..，或者stdbuf -oL printf ...
回答by user3694063
Maybe "stty raw" can help with some other tricks for end-of-lines handling. AFAIK "raw" mode turns off line based buffering, at least when used for serial port ("stty raw < /dev/ttyS0").
也许“stty raw”可以帮助一些其他的行尾处理技巧。AFAIK“原始”模式关闭基于行的缓冲，至少在用于串行端口时（“stty raw < /dev/ttyS0”）。
回答by Dan Hale
If you force the file to be read, it seems to cause the buffer to flush. These work for me.
如果强制读取文件，似乎会导致缓冲区刷新。这些对我有用。
Either read the data into a useless variable:
要么将数据读入一个无用的变量中：
x=$(<$logfile)
Or do a UUOC:
或者做一个UUOC：
cat $logfile > /dev/null
