Standard error doesn't pass through pipes. It goes directly to the terminal. So redirecting the last command only redirects errors the last program prints.
It's extremely wasteful to run awk to process single lines. Might be better to do this:
Faster since it uses less processes, and the error messages can be whatever you'd like.
I came across the following problem, where file contents are overwritten using redirection. Can somebody please explain what cat << BAR seems to be doing and say why this is a problem? Explain the contents and relation between the two filenames used before the cat command. thanks
/tmp# echo... (2 Replies)
Hi,
in my script I need to execute the following command:
query $id 456 432
but it waits for a RETURN character from keyboard and therefore, it fails. I tried something like:
query $id 456 432 << '\n'
but, i'ts clear it is not correct. Is there any way to do this?
Thxs. (0 Replies)
Hi all,
I am working with the Grinder tool (unrelated to my question) to redirect the output of a program to a file as follows:
java -cp $CLASSPATH net.grinder.TCPProxy > grinder.txt
This is a proxy server which pipes output to a file. When I do something on my proxy, more and more goes to... (1 Reply)
Hi all,
Maybe someone is able to help:
Need to redirect the output of a command in realtime to a second command. Command-A executes a remote shell to another host, and outputs its results. Command-B displays a "dialog" with the outputs of Command-A.
Command-A Output:
Updating FileA... (2 Replies)
I just wondered if I'm understanding this command line correctly
cat 2>save1 0<memo | sort 2>save2 1>letter
This means that stdin will read from memo and if there is an error then stderr will write to save1. Am I correct in saying that the sort command will sort the memo file and write... (2 Replies)
for shell operators like <, >, <<, and >> do the LHS always have to be a process or device and the RHS a file or device?
Is it possible for the RHS to be a process? (1 Reply)
I want to redirect stderr and have the following peice of code
$ cat t1.ksh
#!/bin/ksh
func2()
{
diff /tmp/jdlkwjdlkejew /tmp/djlkwejdlewdjew >$OUTPUT_FILE 2>>$ERR_FILE
}
func1()
{
let counter=0
while
do
print -u2 "Error: In main function"
func2
let... (1 Reply)
So I have a existing file that I used the uniq command on and I need to save the output to the same file without changing the file name.
I have tried $ uniq filename > filename
then when I cat the file it then becomes blank like there is nothing inside.
any help would be much appreciated... (0 Replies)
OS : AIX 6.1
Shell : Korn
in the url
https://forums.oracle.com/forums/thread.jspa?threadID=361463&tstart=0
I came across a crontab entry example
00 23 * * 1,3,5 <complete shell script path> 1> <log file> 2>&1
From googling , I gathered that
0 - stdin
1 - stdout
2 - stderr
I... (5 Replies)
Hi,
Can I get some explanation around this bash redirection?
From what I have read, x < y means call the shell to redirect the output of y into x.
Does this mean that this sequence of commands is executed from right to left?
diff <(sort testfile.txt) <(sort testfile2.txt)
Thanks,
edit... (2 Replies)
Discussion started by: sand1234
2 Replies
LEARN ABOUT CENTOS
trace-cmd-restore
TRACE-CMD-RESTORE(1)TRACE-CMD-RESTORE(1)NAME
trace-cmd-restore - restore a failed trace record
SYNOPSIS
trace-cmd restore [OPTIONS] [command] cpu-file [cpu-file ...]
DESCRIPTION
The trace-cmd(1) restore command will restore a crashed trace-cmd-record(1) file. If for some reason a trace-cmd record fails, it will
leave a the per-cpu data files and not create the final trace.dat file. The trace-cmd restore will append the files to create a working
trace.dat file that can be read with trace-cmd-report(1).
When trace-cmd record runs, it spawns off a process per CPU and writes to a per cpu file usually called trace.dat.cpuX, where X represents
the CPU number that it is tracing. If the -o option was used in the trace-cmd record, then the CPU data files will have that name instead
of the trace.dat name. If a unexpected crash occurs before the tracing is finished, then the per CPU files will still exist but there will
not be any trace.dat file to read from. trace-cmd restore will allow you to create a trace.dat file with the existing data files.
OPTIONS -c
Create a partial trace.dat file from the machine, to be used with a full trace-cmd restore at another time. This option is useful for
embedded devices. If a server contains the cpu files of a crashed trace-cmd record (or trace-cmd listen), trace-cmd restore can be
executed on the embedded device with the -c option to get all the stored information of that embedded device. Then the file created
could be copied to the server to run the trace-cmd restore there with the cpu files.
If *-o* is not specified, then the file created will be called
'trace-partial.dat'. This is because the file is not a full version
of something that trace-cmd-report(1) could use.
-t tracing_dir
Used with -c, it overrides the location to read the events from. By default, tracing information is read from the debugfs/tracing
directory. -t will use that location instead. This can be useful if the trace.dat file to create is from another machine. Just tar
-cvf events.tar debugfs/tracing and copy and untar that file locally, and use that directory instead.
-k kallsyms
Used with -c, it overrides where to read the kallsyms file from. By default, /proc/kallsyms is used. -k will override the file to read
the kallsyms from. This can be useful if the trace.dat file to create is from another machine. Just copy the /proc/kallsyms file
locally, and use -k to point to that file.
-o output'
By default, trace-cmd restore will create a trace.dat file (or trace-partial.dat if -c is specified). You can specify a different file
to write to with the -o option.
-i input
By default, trace-cmd restore will read the information of the current system to create the initial data stored in the trace.dat file.
If the crash was on another machine, then that machine should have the trace-cmd restore run with the -c option to create the trace.dat
partial file. Then that file can be copied to the current machine where trace-cmd restore will use -i to load that file instead of
reading from the current system.
EXAMPLES
If a crash happened on another box, you could run:
$ trace-cmd restore -c -o box-partial.dat
Then on the server that has the cpu files:
$ trace-cmd restore -i box-partial.dat trace.dat.cpu0 trace.dat.cpu1
This would create a trace.dat file for the embedded box.
SEE ALSO trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-start(1), trace-cmd-stop(1), trace-cmd-extract(1), trace-cmd-reset(1),
trace-cmd-split(1), trace-cmd-list(1), trace-cmd-listen(1)AUTHOR
Written by Steven Rostedt, <rostedt@goodmis.org[1]>
RESOURCES
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/trace-cmd.git
COPYING
Copyright (C) 2010 Red Hat, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).
NOTES
1. rostedt@goodmis.org
mailto:rostedt@goodmis.org
06/11/2014 TRACE-CMD-RESTORE(1)