linux - How does/frequent unix tee command write stdout terminal output to file? if the output is too big -
i redirecting tool stdout tee command current progress can seen on terminal in log file
here code snippet running tool , stdout fed tee command , code snippet written tcl script.
$(eh_submit) $(icc_exec) $(options) -f ./scripts/$@.tcl | tee -i ./logs/$@.log
i can see current real time progress on terminal same observation not seen in log file! , writes stdout log file chunk chunk
how tee
work? write blocks or time or both? if block minimum block size? if time minimum duration?
i need parse real time log entries data analytics(as read log file via tail -f
, push new data log file grows).
unless programs handle buffering on own, buffering of io streams handled in libc. standard behaviour is: buffer output line wise if goes terminal, buffer output block wise if goes non-terminal, meaning file or pipe. that's why output appears in log file described it: chunk chunk. behaviour performance optimization.
on linux stdbuf
command can used run program adjusted buffers. need run program this:
stdbuf -ol your_program >> your.log & tail -f your.log
-ol
means buffer stdout linewise.
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