cheatsheet

redirect

show stdout but redirect all to file

[!NOTE|label:references:]

          || visible in terminal ||   visible in file   || existing
  SYNTAX  ||  STDOUT  |  STDERR  ||  STDOUT  |  STDERR  ||   FILE
==========++==========+==========++==========+==========++===========
    >     ||    no    |   yes    ||   yes    |    no    || overwrite
    >>    ||    no    |   yes    ||   yes    |    no    ||  append
          ||          |          ||          |          ||
   2>     ||   yes    |    no    ||    no    |   yes    || overwrite
   2>>    ||   yes    |    no    ||    no    |   yes    ||  append
          ||          |          ||          |          ||
   &>     ||    no    |    no    ||   yes    |   yes    || overwrite
   &>>    ||    no    |    no    ||   yes    |   yes    ||  append
          ||          |          ||          |          ||
 | tee    ||   yes    |   yes    ||   yes    |    no    || overwrite
 | tee -a ||   yes    |   yes    ||   yes    |    no    ||  append
          ||          |          ||          |          ||
 n.e. (*) ||   yes    |   yes    ||    no    |   yes    || overwrite
 n.e. (*) ||   yes    |   yes    ||    no    |   yes    ||  append
          ||          |          ||          |          ||
|& tee    ||   yes    |   yes    ||   yes    |   yes    || overwrite
|& tee -a ||   yes    |   yes    ||   yes    |   yes    ||  append

Redirect terminal output to file
Bash: Redirect stdout and stderr
show Command Output Redirection.pdf
3.6 Redirections
* Beyond Linux From Scratch
How do I write standard error to a file while using "tee" with a pipe?

tips:

echo to stderr

$ echo 'abcdefg' >/dev/null
$ echo 'abcdefg' >/dev/null >&2
abcdefg

$ bash -c "echo a;bahs;echo b;bhas" >>file 2> >( tee -a file >&2 )
bash: line 1: bahs: command not found
bash: line 1: bhas: command not found

$ cat file
a
bash: line 1: bahs: command not found
b
bash: line 1: bhas: command not found

stderr output with filter

$ bash -c "echo a;bahs;echo b;bhas" >>file 2> >( tee -a file 2>&1 | grep -v bahs >&2 )
bash: line 1: bhas: command not found
# or
$ rm -rf file; bash -c "echo a;bahs;echo b;bhas" >>file 2> >( tee -a file | grep -v bahs >&2 )
bash: line 1: bhas: command not found

$ cat file
a
bash: line 1: bahs: command not found
b
bash: line 1: bhas: command not found

$ bash -c "set -e; echo a;bahs;echo b;bhas" >>cmd.out 2> >( tee -a cmd.out >&2 )
bash: line 1: bahs: command not found

$ cat cmd.out
a
bash: line 1: bahs: command not found

get output with color code from stderr

$ command kubecolor get pod 2> >(/opt/homebrew/opt/coreutils/libexec/gnubin/cat -v)
^[[31mE^[[0m^[[90;3m0317 14:50:30.321015^[[0m   19219 ^[[90;3mmemcache.go:287^[[0m] ^[[93m"Unhandled Error"^[[0m ^[[96merr^[[0m=^[[93m"couldn't get resource list for metrics.k8s.io/v1beta1: the server is currently unable to handle the request"^[[0m
^[[31mE^[[0m^[[90;3m0317 14:50:31.317212^[[0m   19219 ^[[90;3mmemcache.go:121^[[0m] ^[[93m"Unhandled Error"^[[0m ^[[96merr^[[0m=^[[93m"couldn't get resource list for metrics.k8s.io/v1beta1: the server is currently unable to handle the request"^[[0m
^[[31mE^[[0m^[[90;3m0317 14:50:31.440696^[[0m   19219 ^[[90;3mmemcache.go:121^[[0m] ^[[93m"Unhandled Error"^[[0m ^[[96merr^[[0m=^[[93m"couldn't get resource list for metrics.k8s.io/v1beta1: the server is currently unable to handle the request"^[[0m
^[[31mE^[[0m^[[90;3m0317 14:50:31.558730^[[0m   19219 ^[[90;3mmemcache.go:121^[[0m] ^[[93m"Unhandled Error"^[[0m ^[[96merr^[[0m=^[[93m"couldn't get resource list for metrics.k8s.io/v1beta1: the server is currently unable to handle the request"^[[0m

time & date

[!TIP|label:see also:]
* iMarslo: date
* iMarslo: clock/date/time

show date with timezone

# with quotes
$ TZ=':Asia/Shanghai' date

# or without quotes
$ TZ=America/Los_Angeles date

show cal

$ cal -y

# or
$ cal -y |
      tr '\n' '|' |
      sed "s/^/ /;s/$/ /;s/ $(date +%e) / $(date +%e | sed 's/./#/g') /$(date +%m | sed s/^0//)" |
      tr '|' '\n'
                             2014
      January               February               March
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
          1  2  3  4                     1                     1
 5  6  7  8  9 10 11   2  3  4  5  6  7  8   2  3  4  5  6  7  8
12 13 14 15 16 17 18   9 10 11 12 13 14 15   9 10 11 12 13 14 15
19 20 21 22 23 24 25  16 17 18 19 20 21 22  16 17 ## 19 20 21 22
26 27 28 29 30 31     23 24 25 26 27 28     23 24 25 26 27 28 29
                                            30 31

       April                  May                   June
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
       1  2  3  4  5               1  2  3   1  2  3  4  5  6  7
 6  7  8  9 10 11 12   4  5  6  7  8  9 10   8  9 10 11 12 13 14
13 14 15 16 17 18 19  11 12 13 14 15 16 17  15 16 17 18 19 20 21
20 21 22 23 24 25 26  18 19 20 21 22 23 24  22 23 24 25 26 27 28
27 28 29 30           25 26 27 28 29 30 31  29 30


        July                 August              September
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
       1  2  3  4  5                  1  2      1  2  3  4  5  6
 6  7  8  9 10 11 12   3  4  5  6  7  8  9   7  8  9 10 11 12 13
13 14 15 16 17 18 19  10 11 12 13 14 15 16  14 15 16 17 18 19 20
20 21 22 23 24 25 26  17 18 19 20 21 22 23  21 22 23 24 25 26 27
27 28 29 30 31        24 25 26 27 28 29 30  28 29 30
                      31

      October               November              December
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
          1  2  3  4                     1      1  2  3  4  5  6
 5  6  7  8  9 10 11   2  3  4  5  6  7  8   7  8  9 10 11 12 13
12 13 14 15 16 17 18   9 10 11 12 13 14 15  14 15 16 17 18 19 20
19 20 21 22 23 24 25  16 17 18 19 20 21 22  21 22 23 24 25 26 27
26 27 28 29 30 31     23 24 25 26 27 28 29  28 29 30 31
                      30

synchronize date and time with over ssh

[!NOTE|label:inspired from:]
commandlinefu.com)

$ date --set="$(ssh [username]@[sshserver] date)"

verify

$ date;
  ssh username@sshserver date;
  curl -fsSL "http://worldtimeapi.org/api/timezone/America/Los_Angeles" | jq -r .datetime
Tue Apr  2 20:03:32 PDT 2024
Tue Apr  2 20:03:33 PDT 2024
2024-04-02T20:03:33.405227-07:00

download and extract

[!NOTE|label:references:]
* see also: iMarslo: oneline command

*.gz

$ wget -O - http://example.com/a.gz | tar xz

*.zip

$ curl -fsSL https://services.gradle.org/distributions/gradle-4.7-all.zip | bsdtar xzf - -C <EXTRACT_PATH>

# with password
$ curl -fsSL \
       -u<user>:<passwd> \
       https://path/to/file.zip |
  bsdtar -xzf- --passphrase <PASSWD_OF_ZIP> - -C <EXTRACT_PATH>

*.tar.gz

$ curl -fsSL https://path/to/file.tar.gz | tar xzf - -C <EXTRACT_PATH>

# example
$ curl -fsSL -j -k \
       -H "Cookie: oraclelicense=accept-securebackup-cookie" \
       http://download.oracle.com/otn-pub/java/jdk/8u181-b13/96a7b8442fe848ef90c96a2fad6ed6d1/jdk-8u181-linux-x64.tar.gz |
  tar xzf - -C '/opt/java'

check file without extract

$ tar -Oxvf myfile.tgz path/to/my.sh | less

extract `jar`

$ unzip <jar-name>.jar -d <target-folder>

Delete files from JAR without unzip

$ zip -d <jar-name>.jar <path/to/file.txt>

recursive download

[!TIP] references:
download a directory and subdirectories using wget
wget(1) - Linux man page
params shortcuts :

SHORT PARAMS

LONG PARAMS

-r

--recursive

-m

--mirror

-l

--level

-k

--convert-links

-K

--backup-converted

-P

--directory-prefix

-nv

--no-verbose

-nc

--no-clobber

-nd

--no-directories

-nH

--no-host-directories

-np

--no-parent

-x

--force-directories

-b

--background

-v

--verbose

-p

--page-requisites

$ wget --recursive                       \     # -r
       --user=admin                      \
       --password=admin                  \     # --ask-password
       --auth-no-challenge               \     # optional
       --no-host-directories             \     # -nH
       --no-parent                       \     # -np
       --reject '*.html*'                \
       --directory-prefix=./             \     # -P
       --include-directories=local-dir   \     # -I
  http://example.com/remote-dir

# or
$ wget --recursive                                   \    # -r
       --no-parent                                   \    # -np : will not crawl links in folders above the base of the URL
       --convert-links                               \    # -k  : convert links with the domain name to relative and uncrawled to absolute
       --random-wait --wait 3 --no-http-keep-alive   \    #       do not get banned
       --no-host-directories                         \    # -nH : do not create folders with the domain name
       --execute robots=off --user-agent=Mozilla/5.0 \    #       I AM A HUMAN!!!
       --level=inf --accept '*'                      \    # -l  : do not limit to 5 levels or common file formats
       --reject="index.html*"                        \    #       use this option if you need an exact mirror
       --cut-dirs=0                                  \    #       replace 0 with the number of folders in the path, 0 for the whole domain
  $URL

mirror whole website
```
$ wget -m https://www.baeldung.com/
```

download directly

$ wget -r -np -nH --cut-dirs=1 https://www.baeldung.com/linux
# or
$ wget -r --no-parent --no-host-directories --cut-dirs=1 https://www.baeldung.com/linux

with level

$ wget -r -np -l 2 https://www.baeldung.com/linux/
# or
$ wget -r --no-parent --level=2 https://www.baeldung.com/linux/

with credentials

.wgetrc

$ cat ~/.wgetrc
user=admin
password=admin

from cmd

$ wget --user=admin --password=admin

# or
$ wget --user=admin --ask-password
Password for user 'admin': admin

ignore credentials
```
$ wget --no-check-certificate
```

converting links for local viewing

$ wget -r --no-parent --convert-links https://www.baeldung.com/linux/category/web

switching off robot exclusion

$ wget -r --level=1 --no-parent --convert-links -e robots=off -U="Mozilla"

compress

zip package with dot-file

.[^.]*
```
$ zip name.zip * .[^.]*'
```
shopt -s dotglob
[!NOTE|label:references:]
- imarslo : bash/bash
```
$ shopt -s dotglob
$ zip name.zip *
```
.
```
$ zip -r name.zip .
```

remove dot-file without `skipping '..' '.'` issue

[!NOTE|label:references:]
imarslo : bash/bash
turn dotglob off
$ shopt -u dotglob

shopt -s dotglob
```
$ shopt -s dotglob
$ rm [-rf] *
```
.[^.]*
```
$ rm [-rf] .[^.]*
```
.[!.]*
```
$ rm [-rf] .[!.]*
```
.??*
```
$ rm [-rf] .??*
```
copy all including hidden files
```
$ cp -r * .??* /dest
```

show 256 colors

[!TIP] see also:
imarslo : cheatsheet/colors
imarslo : cheatsheet/tricky.html#highlight-output

$ for i in {0..255}; do echo -e "\e[38;05;${i}m${i}"; done | column -c 80 -s ' '; echo -e "\e[m"
# or
$ yes "$(seq 1 255)" | while read i; do printf "\x1b[48;5;${i}m\n"; sleep .01; done

# or: https://www.commandlinefu.com/commands/view/5879/show-numerical-values-for-each-of-the-256-colors-in-bash
$ for code in {0..255}; do echo -e "\e[38;05;${code}m $code: Test"; done)

# or: https://www.commandlinefu.com/commands/view/6138/show-numerical-values-for-each-of-the-256-colors-in-bash
$ for i in {0..255}; do echo -e "\e[38;05;${i}m${i}"; done | column -c 80 -s ' '; echo -e "\e[m"

# or: https://www.commandlinefu.com/commands/view/11759/show-numerical-values-for-each-of-the-256-colors-in-bash-for-bold-and-normal-fonts
$ for code in $(seq -w 0 255); do for attr in 0 1; do printf "%s-%03s %bTest%b\n" "${attr}" "${code}" "\e[${attr};38;05;${code}m" "\e[m"; done; done | column -c $((COLUMNS*2))
# better vesion
$ for code in $(seq -w 0 255); do for attr in 0 1; do printf "%b%s-%03s%b\n"  "\e[${attr};38;05;${code}m" "${attr}" "${code}" "\e[m"; done; done | column -c $((COLUMNS*3))

# .. zsh ..
# or: https://www.commandlinefu.com/commands/view/5876/show-numerical-values-for-each-of-the-256-colors-in-zsh
$ for code in {000..255}; do print -P -- "$code: %F{$code}Test%f"; done

# or: https://www.commandlinefu.com/commands/view/12471/show-numerical-values-for-each-of-the-256-colors-in-zsh
for i in {0..255}; do echo -e "\e[38;05;${i}m\\\e[38;05;${i}m"; done | column -c 80 -s ' '; echo -e "\e[m"

commands

`ls`

[!TIP|label:references]
Why not parse ls (and what to do instead)?
Why you shouldn't parse the output of ls(1)

list numeric names

[!NOTE|label:references:]
How can I get files with numeric names using ls command?

$ ls git-[[:digit:]]*.png
git-0.png  git-1.png  git-2.png  git-3.png  git-4.png  git-5.png

$ ls git-+([0-9])*.png
git-0.png  git-1.png  git-2.png  git-3.png  git-4.png  git-5.png

PWD's secrets

$ l | grep bc
lrwxrwxrwx 1 marslo marslo   37 Mar  4 00:25 bc -> /home/marslo/Tools/Git/BrowserConfig//
$ cd bc/
$ pwd -L
/home/marslo/bc
$ pwd -P
/home/marslo/Tools/Git/BrowserConfig

list the command startsWith

$ compgen -c "system-config-"
system-config-authentication
system-config-authentication
system-config-date
system-config-firewall
system-config-firewall-tui
system-config-kdump
system-config-keyboard
system-config-keyboard
system-config-network
system-config-network
system-config-network-cmd
system-config-network-cmd
system-config-network-tui
system-config-printer
system-config-printer-applet
system-config-services
system-config-services
system-config-users

fuzzy find for commands

$ apropos editor | head
Git::SVN::Editor (3pm) - commit driver for "git svn set-tree" and dcommit
INIFILE (1)          - OpenLink Virtuoso Opensource ini File Editor
atobm (1)            - bitmap editor and converter utilities for the X Window System
bitmap (1)           - bitmap editor and converter utilities for the X Window System
bmtoa (1)            - bitmap editor and converter utilities for the X Window System
ed (1)               - line-oriented text editor
editor (1)           - Nano's ANOther editor, an enhanced free Pico clone
editres (1)          - a dynamic resource editor for X Toolkit applications
ex (1)               - Vi IMproved, a programmers text editor
gedit (1)            - text editor for the GNOME Desktop

batch commands

batch rename

$ l
total 4.0K
-rw-r--r-- 1 marslo marslo 10 Feb 21 00:43 a.b
$ rename -v 's/\./_/g' *
a.b renamed as a_b
$ l
total 4.0K
-rw-r--r-- 1 marslo marslo 10 Feb 21 00:43 a_b

delete string with find

$ for file in sw.ras.*; do mv "$file" "${file/ras./}"; done

/usr/local/bin/rename in OSX

$ /usr/local/bin/rename -v 's/_xyz.com//g' *.txt
'a_xyz.com.txt' renamed to 'a.txt'
'b_xyz.com.txt' renamed to 'b.txt'
'c_xyz.com.txt' renamed to 'c.txt'
'd_xyz.com.txt' renamed to 'd.txt'
'e_xyz.com.txt' renamed to 'e.txt'
'f_xyz.com.txt' renamed to 'f.txt'
'g_xyz.com.txt' renamed to 'g.txt'
'h_xyz.com.txt' renamed to 'h.txt'

rename from util-linux

[!NOTE|label:references:]
Rename multiple files based on pattern in Unix

$ /usr/local/opt/util-linux/bin/rename -v '_xyz.com' '' *.ttf
`a_xyz.com.ttf' -> `a.ttf'
`b_xyz.com.ttf' -> `b.ttf'
`c_xyz.com.ttf' -> `c.ttf'
`d_xyz.com.ttf' -> `d.ttf'
`e_xyz.com.ttf' -> `e.ttf'
`f_xyz.com.ttf' -> `f.ttf'
`g_xyz.com.ttf' -> `g.ttf'
`h_xyz.com.ttf' -> `h.ttf'

xargs rename

$ shopt -s extglob
$ ls git-+([0-9])*.png
git-0.png  git-1.png  git-2.png  git-3.png  git-4.png  git-5.png

$ ls --color=none git-+([0-9])*.png | xargs rename -v 's/git-/git-for-windows-/'
'git-0.png' renamed to 'git-for-windows-0.png'
'git-1.png' renamed to 'git-for-windows-1.png'
'git-2.png' renamed to 'git-for-windows-2.png'
'git-3.png' renamed to 'git-for-windows-3.png'
'git-4.png' renamed to 'git-for-windows-4.png'
'git-5.png' renamed to 'git-for-windows-5.png'

batch move

[!NOTE]-I replace-str

$ mkdir backup-folder && ls | grep -Ze ".*rar" | xargs -d '\n' -I {} mv {} backup-folder

batch copy

reference:
Hack 22. Xargs Command Examples

$ ls -1 a/b/* 11 12 | xargs cp -t copy-target-folder/

copy single file to multipule folders

$ echo dir1 dir2 dir3 | xargs -n 1 cp file1

# or
$ echo dir{1..10} | xargs -n 1 cp file1

ldapsearch

[!NOTE] enhaanced script

-LLL                                          # just a particular way to display the results
-H ldap://wspace.mydomain.com                 # the URL where the LDAP server listens
-x                                            # use simple authentication, not SASL
-D 'user1'                                    # the account to use to authenticate to LDAP
-w 'user1password'                            # the password that goes with the account on the previous line
-E pr=1000/noprompt                           # ask the server for all pages, don't stop after one
-b 'ou=mydomain,dc=wspace,dc=mydomain,dc=com' # the base of the search. We don't want results from e.g. 'ou=blah,dc=wspace,dc=mydomain,dc=com'
'(&(objectClass=person)(uidNumber=*))'        # Ask for any entry that has attributes objectClass=person and uidNumber has a value
SAMAccountName uid uidNumber                  # Show only these attributes

search specific user

[!NOTE] info :
ldap url : ldaps://ldap.mydomain.com:636
base search base : dc=mydomain,dc=com
login user : user1 / user1password
search : user2
remove #refldaps://..
remove #.*
$ ldapsearch ... | sed -r '/^(#.*)$/d'
remove empty lines
$ ldapsearch ... | sed -r '/^\s*$/d'
remove all
$ ldapsearch ... | sed -r '/^(#.*)$/d;/^\s*$/d'

# or
$ ldapsearch ... | sed -r '/(^#.*)|(^\s*)$/d'

$ ldapsearch \
    -LLL \
    -x \
    -H 'ldaps://ldap.mydomain.com:636' \
    -b 'dc=mydomain,dc=com' \
    -D 'user1' \
    -w 'user1password' \
    CN='user2'

or insert password via interactive mode ( -W )

$ ldapsearch \
    -LLL \
    -x \
    -H 'ldaps://ldap.mydomain.com:636' \
    -b 'dc=mydomain,dc=com' \
    -W \
    -D 'user1' \
    CN='user2'

filter `DN` field only

$ ldapsearch \
    [-LLL \]
    -H 'ldaps://ldap.mydomain.com:636' \
    -b 'dc=mydomain,dc=com' \
    -x \
    -D 'user1' \
    -w 'user1password' \
    CN='user2' \
    DN

filter `SAMAccountName`, `uid` and `uidNumber` only

[!TIP] filter base on base DN (OU=Person,DC=mydomain,DC=com)

$ ldapsearch \
    -LLL \
    -x \
    -H 'ldaps://ldap.mydomain.com:636' \
    -b 'ou=Workers,dc=mydomain,dc=com' \
    -D 'user1' \
    -w 'user1password' \
    -E 'pr=1000/noprompt' \
    '(&(objectClass=user)(sAMAccountName=*))' \
    SAMAccountName uid uidNumber DN

filter particular group

$ ldapsearch \
    -x \
    -H 'ldaps://ldap.mydomain.com:636' \
    -b 'OU=DL,OU=Groups,OU=GLOBAL,OU=Sites,dc=mydomain,dc=com' \
    -D 'user1' \
    -w 'user1password' \
    -E 'pr=1000/noprompt' \
    '(&(objectClass=group)(CN=*))'

search particular group (cn=DL-name-group)

$ ldapsearch \
    -x \
    -H 'ldaps://ldap.mydomain.com:636' \
    -b 'OU=DL,OU=Groups,OU=GLOBAL,OU=Sites,dc=mydomain,dc=com' \
    -D 'user1' \
    -w 'user1password' \
    -E 'pr=1000/noprompt' \
    CN='DL-name-group'

get userCertificates

[!NOTE|label:references:]

Problems with ldap userCertificate attribute

9.2. Certificate Publishing

# convert a pem certificate into der
openssl x509 -outform DER -in incert.pem  -out outcert.der

# created LDIF file
ldif -b "usercertificate;binary" < outcert.der  > cert.ldif

# creates an usercertificate attribute encoded in base64
ldapmodify -x -W -D "cn=Manager,dc=yourorg,dc=com" -f cert.ldif

get cert info

$ ldapsearch marslo userCertificate |
             awk '{print $NF}' |
             xargs -i bash -c "echo {} | base64 -d -w0 | openssl x509 -noout -dates -subject -issuer"

# or
$ while read -r crt; do
    echo "${crt}" | base64 -d -w0 | openssl x509 -noout -dates -subject -issuer;
  done < <(ldapsearch marslo userCertificate | awk '{print $NF}')
notBefore=Apr 28 18:05:13 2023 GMT
notAfter=Apr 27 18:05:13 2025 GMT
subject=DC = com, DC = example, OU = Workers, CN = marslo, emailAddress = marslo@example.com
issuer=DC = com, DC = example, CN = example SC Issuing CA V1

save local

der

$ while read -r n c; do
    echo "-- ${n} --";
    echo "${c}" | base64 -d -w0 > cert_${n}.der;
  done < <(ldapsearch marslo userCertificate | awk '{print $NF}' | cat -n)

crt

$ while read -r n c; do
    echo "-- ${n} --";
    echo "${c}" | base64 -d -w0 > cert_${n}.der;
    openssl x509 -in cert_${n}.der -inform DER -out cert_${n}.crt;
  done < <(ldapsearch marslo userCertificate | awk '{print $NF}' | cat -n)

others

directory diff

$ diff --suppress-common-lines -y <(cd path_to_dir1; find .|sort) <(cd path_to_dir2; find .|sort)

show some command periodically

$ watch --interval 1 ls -alt

watch with pipe

$ watch -n 1 'ls -Altrh | grep <keywords>'

clear

$ printf "\ec"

use less as tail -f

$ less +F <filename>

netcat & nmap-ncat

[!NOTE] references:
* imarslo : epel
* imarslo : adminTools - nc

install

$ sudo yum -y install epel-release [yum-utils]
# or via url
$ sudo dnf [re]install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
$ sudo dnf [re]install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

$ sudo yum update -y
$ yum list | grep netcat
netcat.x86_64      1.219-2.el8       @epel
$ sudo yum install -y netcat.x86_64

# check
$ sudo yum repolist

switch with nmap & netcat

$ ls -altrh /usr/local/bin/nc
lrwxrwxrwx 1 root root 22 Mar 14 03:14 /usr/local/bin/nc -> /etc/alternatives/nmap

$ sudo update-alternatives --config nmap

There are 2 programs which provide 'nmap'.

  Selection    Command
-----------------------------------------------
*+ 1           /usr/bin/ncat
   2           /usr/bin/netcat

Enter to keep the current selection[+], or type selection number: 2

check

# by using netcat
$ nc -zv google.com 443
Connection to google.com (142.251.214.142) 443 port [tcp/https] succeeded!

# by using nact
$ ncat -zv google.com 443
Ncat: Version 7.70 ( https://nmap.org/ncat )
Ncat: Connected to 142.251.214.142:443.
Ncat: 0 bytes sent, 0 bytes received in 0.07 seconds.

check package

$ rpm -ql netcat.x86_64
/usr/bin/nc
/usr/bin/netcat
/usr/lib/.build-id
/usr/lib/.build-id/f3
/usr/lib/.build-id/f3/3de6290429f99a8d8f5fe646a93bcc952dafdd
/usr/share/man/man1/nc.1.gz
/usr/share/man/man1/netcat.1.gz

$ rpm -ql nmap-ncat.x86_64
/usr/bin/nc
/usr/bin/ncat
...

alternatives & update-alternatives