Effect of using eval to execute a command as opposed to writing it on the commandline
If this script is executed, an error is generated. The reason written was that "The execution fails because the pipe is not expanded and is passed to date as an argument". What is meant by expansion of pipe. When we execute date | wc on the command line, it goes fine. then | is not treated as an argument. Why?
If I write
It works. How?
I understand (hopefully) how eval works in 2 passes i.e. the command first gets evaluated and then executed.
Hi
i have the following code:
if(($line!=1) and (@field!='\$')){
print ( "\nTRY TO CONNECT TO DATABASE................\n");
my $dbh = DBI->connect($dsn, $user, $pass);
print ("CONNECTED TO DATABASE\n");
eval
... (1 Reply)
Hi All,
i have an issue regarding trap command.
i have specified trap function in the beginning of the script to catch some signals but in the later part of the script i want to remove the effect of this.
Can anybody help me out of this.
for e.g. pressing Ctrl+C for the first time should... (2 Replies)
Hi Gurus,
I am having 2 parameters as below
parm1=value1
parm2=parm1
I want to evaluate parm1 value using eval echo \$$parm2 and later i want to assign this value to other variable which i will be using in if statement like :
if ]; then
do this.......
fi
could you please suggest... (5 Replies)
I have file called myfile which has the text "myserver" in it. I need to have a command to ping "myserver". How would I do that?
I tried
when I type at the terminal I get the output as . How do I do something like a ?
thanks,
Nick (5 Replies)
Hi all,
some small script with eval turned me to crazy.
my OS is linux
Linux s10-1310 2.6.16.53-0.8.PTF.434477.3.TDC.0-smp #1 SMP Fri Aug 31 06:07:27 PDT 2007 x86_64 x86_64 x86_64 GNU/Linux
below script works well
#!/bin/bash
eval ssh remotehost date
eval ssh remotehost ls
below... (1 Reply)
Hi All,
I read the above written code (perl code) in another perl script and evaluates this code for each line of text file,but using exit statement in code make this not to work and i could not get the desired results. However if i use return it works fine. I just need to know why it doesn't... (1 Reply)
When i run the command sudo /usr/sbin/prtdiag manually on a solaris 10 box, it works as expected.
But the same command from my java code gives me the following error. picl_initialize failed: Daemon not responding.
I am unable to figure out why is not running from my code.:wall: (3 Replies)
Hi,
I am trying to use eval command to evaluate a variable(HAPROXY_LISTENER_rabbitmq_project-test-BRHM_PORT) which consists of '-' but unfortunately the eval command is unable to interpret the value of variable and trims the variable name after '-' and produces the string output rather than the... (10 Replies)
Discussion started by: Kuldip
10 Replies
LEARN ABOUT CENTOS
trace-cmd-reset
TRACE-CMD-RESET(1)TRACE-CMD-RESET(1)NAME
trace-cmd-reset - turn off all Ftrace tracing to bring back full performance
SYNOPSIS
trace-cmd reset [OPTIONS]
DESCRIPTION
The trace-cmd(1) reset command turns off all tracing of Ftrace. This will bring back the performance of the system before tracing was
enabled. This is necessary since trace-cmd-record(1), trace-cmd-stop(1) and trace-cmd-extract(1) do not disable the tracer, event after the
data has been pulled from the buffers. The rational is that the user may want to manually enable the tracer with the Ftrace pseudo file
system, or examine other parts of Ftrace to see what trace-cmd did. After the reset command happens, the data in the ring buffer, and the
options that were used are all lost.
OPTIONS -b buffer_size
When the kernel boots, the Ftrace ring buffer is of a minimal size (3 pages per CPU). The first time the tracer is used, the ring
buffer size expands to what it was set for (default 1.4 Megs per CPU).
If no more tracing is to be done, this option allows you to shrink the
ring buffer down to free up available memory.
trace-cmd reset -b 1
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-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-RESET(1)