char* defangIPaddr(const char* address)
{
char* defanged;
int ip[4];
if (sscanf(address, "%d.%d.%d.%d", &ip[0], &ip[1], &ip[2], &ip[3]) != 4)
return NULL;
if (asprintf(&defanged, "%d[.]%d[.]%d[.]%d", ip[0], ip[1], ip[2], ip[3]) == -1)
return NULL;
return defanged;
}
root@box:/# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 ...
2: eno3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 ...
3: eno1np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 ...
4: eno2np1: <BROADCAST,MULTICAST> mtu 1500 ...#!/usr/bin/expect
spawn sudo apt-get -y install cuda
expect "first prompt:"
send "31\r"
expect "second prompt:"
send "1\r"
waitsudo service NetworkManager start|stop|... sudo systemctl start|stop|... NetworkManager sudo systemctl start|stop|... NetworkManager.service
sudo systemctl restart NetworkManager
... jq is a command-line tool for parsing and manipulating JSON data. It is written in C and has a lightweight, minimalistic and flexible syntax. It allows you to filter, extract, and transform JSON data quickly and easily, making it a powerful tool for data processing and analysis.jq was created by Steve Kemp. He started working on jq in early 2011, and the first version was released in April of that year. The tool quickly gained popularity among developers and data analysts, and it has since become one of the most widely used command-line JSON processors.
jq reads JSON data from input and applies a series of filters to it, producing one or more outputs. The filters are written in a domain-specific language (DSL) that is similar to the one used in functional programming languages like Haskell, Lisp and Ruby.
jq supports a wide range of filter types that can be used to select, extract, and modify JSON data, common ones are:Selectors: Select specific parts of JSON data.Functions: Built-in functions that can be used to perform various operations on the input JSON data.Operators: Used to perform mathematical, logical, and comparison operations on the input JSON data.Pipe: Used to connect multiple filters together, where the output of one filter is passed as input to the next filter.
jq supports several types of data, including:Numbers: Integers and floating-point values, such as 42, 3.14, and -2.Strings: Text enclosed in double quotes, such as “hello world”.Booleans: true and false.Arrays: Lists of values enclosed in square brackets, such as [1, 2, 3].Objects: Key-value pairs enclosed in curly braces, such as {“name”: “Tony”, “age”: 100}.Null: The special value null.
jq uses the Oniguruma regular expression library, as do php, ruby, TextMate, Sublime Text, etc, so the description here will focus on jq specifics.The jq regex filters are defined so that they can be used using one of these patterns:STRING | FILTER( REGEX )STRING | FILTER( REGEX; FLAGS )STRING | FILTER( [REGEX] )STRING | FILTER( [REGEX, FLAGS] )
$ cat file.json | jq '.[] | select(.email | test("^[a-z]+@"))'
$ cat file.json | jq '.[] | select(.email | test("^[a-z]+@") | not)'kubectl get --raw "..." | jq .
$ echo '{"name": "Tony", "age": 100}' | jq .
{
"name": "Tony",
"age": 100
}{
"DBClusterSnapshots": [
{
...
"Status": "copying",
...
}
]
}jq -r .DBClusterSnapshots[0].Status
jshon -e DBClusterSnapshots -e 0 -e Status -u
$ echo '[1, 2, 3]' | jq '.[1]' 2
$ echo '[{"name": "Tony", "age": 100}, {"name": "Jane", "age": 25}]' | jq '.[].name'
"Tony"
"Jane"~ curl -X GET -H "Accept: application/vnd.kafka.avro.v2+json" \http://localhost:... | jq[{"topic": "movies","key": null,"value": {"id": 294,"title": "Die Hard","release_year": 1988},"partition": 0,"offset": 0},...]
~ curl -X GET -H "Accept: application/vnd.kafka.avro.v2+json" \http://localhost:... | jq \| jq '.[] | {title: .value.title, year: .value.release_year}'{"title": "Die Hard","year": 1988}{"title": "Tree of Life","year": 2011}{"title": "A Walk in the Clouds","year": 1995}{"title": "The Big Lebowski","year": 1998}{"title": "Super Mario Bros.","year": 1993}{"title": "Chariots of Fire","year": 1981}
$ echo '[1, 2, 3]' | jq 'length' 3
$ cat file.json | jq '.[] | select(.name == "Tony")' $ cat file.json | jq '.[] | select(.age > 100)' $ cat file.json | jq '.[] | select(.age >= 100)' $ cat file.json | jq '.[] | select(.age > 100 and .gender == "male")' $ cat file.json | jq '.[] | select(.age > 100 or .gender == "female")'
{jq -n --arg key APP-Service1-Admin '{($key): $ARGS.positional}' --args a b jq -n --arg key APP-Service1-View '{($key): $ARGS.positional}' --args c d } // Output { "APP-Service1-Admin": [ "a", "b" ] } { "APP-Service1-View": [ "c", "d" ] }
$ ip -details -json link show | jq --join-output '...'jq -r '.Policy'Don't confuse support and stability.LTS releases offer "stability" in the sense that the software does not change for 5 years, not the sense that it crashes less often. The latter coincidentally does happen to be somewhat true also, but that's due to the large user base discovering and filing bugs.
A common problem occurs when folks mistakenly consider an LTS to be a "stable base system" that they can bolt newer software onto. This is precisely the opposite of what an LTS is designed for. If you want newer software, use a newer release of Ubuntu. The Interim (6-month) releases are just as stable for most users as LTS... AND have newer kernel and software.
$ ubuntu-security-status
2258 packages installed, of which:
1745 receive package updates with LTS until 4/2025
499 could receive security updates with ESM Apps until 4/2030
1 package is from a third party
13 packages are no longer available for downloadA command substitution $(...) will be replaced by the output of the command, while a process substitution <(...) will be replaced by a filename from which the output of the command may be read. The command, in both instances, will be run in a subshell.
(list)list is executed in a subshell environment (see COMMAND EXECUTION ENVIRONMENT below). Variable assignments and builtin commands that affect the shell's environment do not remain in effect after the command completes. The return status is the exit status of list.
{ list; }list is simply executed in the current shell environment. list must be terminated with a newline or semicolon. This is known as a group command. The return status is the exit status of list. Note that unlike the metacharacters ( and ), { and } are reserved words and must occur where a reserved word is permitted to be recognized. Since they do not cause a word break, they must be separated from list by whitespace or another shell metacharacter.
no_func || (
echo "there is nothing"
exit 1
)
echo $?$ ./script1.sh
./script1.sh: line 3: no_func: command not found
there is nothing
1 # <-- exit status of subshell
$ echo $?
0 # <-- exit status of scriptno_func || {
echo "there is nothing"
exit 1
}
echo $?/Users/myname/bin/ex5: line 34: no_func: command not found
there is nothing
The parentheses () open a new subshell that will inherit the environment of its parent. However, the subshell will exit as soon as the commands running it it are done, returning you to the parent shell and the cd will only affect the subshell, therefore your PWD will remain unchanged.However, note that the subshell will also copy all shell variables, so you cannot pass information back from the subshell function to the main script via global variables.
doStuffAt() (
cd -- "$1" || exit # the subshell if cd failed.
# do stuff
)systemd gives us the systemctl command which is mostly used to enable services to start at boot time. We can also start, stop, reload, restart and check status of services with the help of systemctl.Ubuntu 15.04'ten itibaren bu yapıya geçmeye başladı.
We can do sudo systemctl enable service_name, and the service will automatically start at boot time. We can also disable services not to start at boot time.
#!/bin/sh
service=$1
if
systemctl | grep -q "$service"
then
systemctl status "$service"
else
echo "The service doesn't exist"
fisystemctl daemon-reloadsudo systemctl start zookeeper sudo systemctl status zookeeper
Running systemctl disable removes the symlink to the service in /etc/systemd/system/*.Örnek
From now on, that service won't start on boot anymore.
systemctl disable snmpdsudo systemctl disable apache2sudo systemctl enable /etc/systemd/system/macoverride.servicesystemctl enable --nowsystemctl is-active --quiet myservicesystemctl is-active --quiet service && echo Service is running# systemctl isolate maintenance.target# systemctl isolate multi-user.targetsystemd units can be listed with systemctl list-units for currently active and systemctl -a list-units for all known units.Örnek
systemctl list-units | grep -E 'service.*running'sudo systemctl mask poweroff.target
...
sudo systemctl unmask poweroff.targetsystemctl reboot --firmware-setupsystemctl restart NetworkManagersystemctl restart sshdShow properties of one or more units, jobs, or the manager itself. If no argument is specified, properties of the manager will be shown. If a unit name is specified, properties of the unit are shown, and if a job ID is specified, properties of the job are shown. By default, empty properties are suppressed. Use --all to show those too. To select specific properties to show, use --property=. ThisŞöyle yaparız.
command is intended to be used whenever computer-parsable output is required. Use status if you are looking for formatted human-readable output.
$ systemctl show -p SubState --value NetworkManager
running$ systemctl show -p ActiveState --value x11-common
inactive
$ systemctl show -p SubState --value x11-common
deadsystemctl enable ssmatt.service
systemctl start ssmatt.servicesystemctl status├─systemd-journald.service
│ └─318 /lib/systemd/systemd-journald
├─fwupd.service
│ └─1703 /usr/lib/fwupd/fwupd
├─systemd-networkd.service
│ └─395 /lib/systemd/systemd-networkd
└─cups-browsed.service
└─2918 /usr/sbin/cups-browsed
lines 172-194/194 (END)systemctl status bluetooth
bluetooth.service - Bluetooth service
Loaded: loaded ...
Active: inactive (dead)
Docs: man:bluetoothd(8)systemctl status sshdsystemd(1)───foo(37775)─┬─{foo1}(37782)
├─{foo2}(37783)
└─{foo3}(37784)$ systemctl status 37775systemctl stop snmpd
Örneksystemctl stop media-backup.automountsystemctl stop "$(systemd-escape -p --suffix=automount /media/backup)"-t, --type=
The argument should be a comma-separated list of unit types such as
service and socket.
If one of the arguments is a unit type, when listing units, limit
display to certain unit types. Otherwise, units of all types will
be shown.
As a special case, if one of the arguments is help, a list of
allowed values will be printed and the program will exit.
--state=
The argument should be a comma-separated list of unit LOAD, SUB, or
ACTIVE states. When listing units, show only those in the specified
states. Use --state=failed to show only failed units.
As a special case, if one of the arguments is help, a list of
allowed values will be printed and the program will exit.systemctl --type=service --state=running list-unitssystemctl --user enable my_example.service
systemctl --user start my_example.service
...
systemctl --user stop my_example.service
systemctl --user status my_example.service