06-09-2009
head command with more than one file
Hi, I have the following problem. I have files with one column of data (let's say file1.dat, file2.dat...file6.dat), and I would like to record the first value of the column of each file into another file (let's name it fileall.dat), which would have the the six values, one in each column. I use to do it as follows,
head --lines=1 file_i.dat >> record_i.dat
with i={1,...,6}, and then, I pasted all with
paste -d" " record_1.dat record_2.dat ... record_6.dat > fileall.dat
and then I had the 6 first values of each data file column together in one file. Is there any way to do it all in one step?
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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)