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Diffstat (limited to 'hurd/debugging/translator/capturing_stdout_and_stderr.mdwn')
| -rw-r--r-- | hurd/debugging/translator/capturing_stdout_and_stderr.mdwn | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/hurd/debugging/translator/capturing_stdout_and_stderr.mdwn b/hurd/debugging/translator/capturing_stdout_and_stderr.mdwn new file mode 100644 index 00000000..b7cfc3c9 --- /dev/null +++ b/hurd/debugging/translator/capturing_stdout_and_stderr.mdwn @@ -0,0 +1,37 @@ +[[!meta copyright="Copyright © 2008, 2009, 2010 Free Software Foundation, +Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled +[[GNU Free Documentation License|/fdl]]."]]"""]] + +Sometimes it may already be helpful to capture a translator's `stdout` and +`stderr`, for example in this situation where [[translator/pfinet]] was +silently dying all the time, without any console output: + + $ sudo settrans -fgap ↩ + /servers/socket/2 ↩ + /bin/sh -c '/hurd/pfinet -i eth0 -a [...] > /tmp/stdout 2> /tmp/stderr' + $ [...] + $ cat /tmp/stdout + NET4: Linux TCP/IP 1.0 for NET4.0 + IP Protocols: ICMP, UDP, TCP + TCP: Hash tables configured (ehash 65536 bhash 65536) + $ cat /tmp/stderr + pfinet: ../../hurd.work/pfinet/ethernet.c:196: ethernet_xmit: Unexpected error: (os/device) invalid IO size. + +(Trying to run [[GDB]] in this case was of no help -- due to a bug in GDB +(supposedly) it wouldn't catch the fault.) + +Be made aware that both `stdout` and `stderr` will be block bufferend and no +longer line buffered when doing such a redirection, so you'll have to arrange +for appropriate `fflush`es on these, or force them to be line buffered again +using the appropriate glibc magic (`setvbuf`). Otherwise you'll see text in +the output files only if either glibc herself decides to flush (after some KiB +of text) the after translator exits. + +There is also a [[related open issue|open_issues/translator_stdout_stderr]]. |