The Xcode console has a 'Debugger output' filter. I understand this is for use with lldb, and that you can get messages to print to this output by using breakpoints. My question is not how to do that.
My question is: what is the underlying mechanism Xcode itself uses to write lldb messages to Debugger Output (not Target Output)? Is there a variable similar to stdout or stderr that writes here? Is it possible, from Xcode target code (Swift/Obj-C/C), to write to this output?
Looks like Xcode uses a tty to communicate with lldb, and you can interface with the Debugger Output using that:
echo "Wheeeeeeee" > $(lsof -p $(ps -A | grep -m1 MacOS/Xcode | awk '{print $1}') | grep -m2 dev/ttys | tail -1 | awk '{print $9}')
Breaking the above down:
$ ps -A | grep -m1 MacOS/Xcode | awk '{print $1}'
21280
This gives the process ID of Xcode (21280). Using this, we can find the files it has open:
$ lsof -p 21280 | grep /dev/ttys
Xcode 21280 tres 47u CHR 16,3 0t0 3569 /dev/ttys003
Xcode 21280 tres 58u CHR 16,5 0t0 3575 /dev/ttys005
The one with the highest number (/dev/ttys005 in this case) is the one we want, so let's extract it. tail -1 will give us the last line of output, and awk '{print $9}' will give us the 9th item on the line, which is what we want!
$ lsof -p 21280 | grep /dev/ttys | tail -1 | awk '{print $9}'
/dev/ttys005
Now we can use this to write whatever we want:
Related
Problem Set (Raspberry Pi OS):
I have a file example.conf that contains a line IPv4addr=XXXXX. I am attempting to change this to the IP that is generated the in the command
ipTest=$(ip --brief a show | grep eth0 | awk '{ print $3 }')
I want to automate this file change during a script install.sh, the line I am attempting is:
IPtest=$(ip --brief a show | grep eth0 | awk '{ print $3 }')
sudo sed -e "/IPv4addr/s/[^=]*$/$IPtest/" example.conf
Returns error:
sed: -e expression #1, char 32: unknown option to `s'
A simple line in that code works, such as SimpleTest='Works'
Any thoughts? I am open to other solutions as well, however I am not an experienced linux user so I am using the tools I know to work with other problem sets.
$IPtest contains the / character; try something like this:
IPtest=$(ip --brief a show | grep eth0 | awk '{ print $3 }')
sudo sed -e '/IPv4addr/s#[^=]*$#'"$IPtest"'#' example.conf
You can shorten your variable and allow awk to do the job of grep at the same time
IPtest=$(ip --brief a s | awk '/eth0/{print $3}')
Using sed grouping and back referencing
sed -i.bak "s|\([^=]*.\).*|\1$IPtest|" example.conf
I am trying to create an Ansible playbook to pull out MTU size for exact NIC (unfortunately i have 5k VMs and this exact NIC does not have the same name on all VMs). I need to parse IP from file to variable and grep by that.
My command i will use in playbook:
/sbin/ifconfig -a | grep -C 1 $IP | grep MTU | awk '{print $5}' | cut -c 5-10
And output should be looking like this:
9000
This one gnu awk command should do:
ifconfig -a | awk -v ip="$IP" -v RS= -F'MTU:' '$0~ip {split($2,a," ");print a[1]}'
9216
Another variations
ifconfig -a | awk -v ip="$IP" 'f {split($6,a,":");print a[2];exit} $0~ip{f=1}'
ifconfig -a | awk -v ip="$IP" 'f {print substr($6,5,99);exit} $0~ip{f=1}'
9216
Friends,
I'm trying to extract the last part of following path in a ksh script:
TOOL_HOME=/export/fapps/mytool/mytool-V2-3-4
I want to extract the version # (i.e., 2-3-4) from the above.
awk runs fine on SuSE:
echo $TOOL_HOME | awk -F'mytool-V' '{print $2}'
#2-3-4
However, on Solaris 10, it produces the following:
#ytool
So on Solaris, awk is ignoring everything after the first character in -F'mytool-V'
What should i do to get the same output on both OS's?
On Solaris use /usr/xpg4/bin/awk, not /bin/awk (aka "old, broken awk").
Solaris awk is broken...
$ echo "$TOOL_HOME" | awk '{sub(/.*mytool-V/,"")}1'
2-3-4
or simply with sed
$ echo "$TOOL_HOME" | sed 's/.*mytool-V//'
2-3-4
No need to use awk or any other external program. ksh can do that:
echo ${TOOL_HOME##*mytool-V}
I wrote a program to analyze the log files in real time. I need to feed it with the IPs. It works fine with the command:
cat /var/log/apache2/access.log | awk '{print $1}' | ./my_program
Also, I can get the IPs in real time with the command:
tail -f /var/log/apache2/access.log | awk '{print $1}'
When I pipe it to my program, my program does not receive anything:
tail -f /var/log/apache2/access.log | awk '{print $1}' | ./my_program
It seems like a matter of buffering. Is there way of piping continuous stream to my program?
I found the ultimate solution to my buffering problem here.
The problem is that stdio is being buffered, ...
I am trying to pipe tshark output to awk. The tshark command works fine on its own, and when piped to other programs such as cat, it works fine (real time printing of output). However, when piped to awk, it hangs and nothing happens.
sudo tshark -i eth0 -l -f "tcp" -R 'http.request.method=="GET"' -T fields -e ip.src -e ip.dst -e
tcp.srcport -e tcp.dstport -e tcp.seq -e tcp.ack | awk '{printf("mz -A %s -B %s -tcp \"s=%s sp=%s
dp=%s\"\n", $2, $1, $5, $4, $3)}'
Here is a simplier version:
sudo tshark -i eth0 -f "tcp" -R 'http.request.method=="GET"' | awk '{print $0}'
And to compare, the following works fine (although is not very useful):
sudo tshark -i eth0 -f "tcp" -R 'http.request.method=="GET"' | cat
Thanks in advance.
I had the same problem.
I have found some partial "solutions" that are not completely portable.
Some of them point to use the fflush() or flush() awk functions or -W interactive option
http://mywiki.wooledge.org/BashFAQ/009
I tried both and none works. So awk is not the appropriate command at all.
A few of them suggest to use gawk but it neither does the trick for me.
cut command has the same problem.
My solution: In my case I just needed to put --line-buffered in GREP and not touching awk command but in your case I would try:
sed -u
with the proper regular expression. For example:
sed -u 's_\(.*\) \(.*\) \(.*\) DIFF: \(.*\)_\3 \4_'
This expression gives you the 3rd and 4th columns separate by TAB (written with ctrl+v and TAB combination). With -u option you get unbuffered output and also you have -l option that gives you line buffered output.
I hope you find this answer useful although is late
Per our previous messages in comments, maybe it will work to force closing the input and emitting a linefeed.
sudo tshark -i eth0 -f "tcp" -R 'http.request.method=="GET"' ...... \
| {
awk '{print $0}'
printf "\n"
}
Note, no pipe between awk and printf.
I hope this helps.
I found the solution here https://superuser.com/questions/742238/piping-tail-f-into-awk (by John1024).
It says:
"You don't see it in real time because, for purposes of efficiency, pipes are buffered. tail -f has to fill up the buffer, typically 4 kB, before the output is passed to awk."
The proposed solutions is to use "unbuffer" or "stdbuf -o0" commands to disable buffering. It worked for me like this:
stdbuf -o0 tshark -i ens192 -f "ip" | awk '{print $0}'