cheatsheet

• redirect

  • show stdout but redirect all to file

  • get output with color code from stderr

• time & date

  • show date with timezone

  • show cal

  • synchronize date and time with over ssh

• download and extract

  • check file without extract

  • extract jar

  • recursive download

• compress

  • zip package with dot-file

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

• show 256 colors

• commands

  • ls

  • PWD's secrets

  • list the command startsWith

  • fuzzy find for commands

• batch commands

  • batch rename

  • xargs rename

  • batch move

  • batch copy

  • copy single file to multipule folders

• ldapsearch

  • search specific user

  • filter DN field only

  • filter SAMAccountName, uid and uidNumber only

  • filter particular group

  • get userCertificates

• others

  • directory diff

  • show some command periodically

  • clear

  • use less as tail -f

  • netcat & nmap-ncat

  • alternatives & update-alternatives

  • polar clock

  • take screenshots of websites from terminal

redirect

show stdout but redirect all to file

[!NOTE|label:references:]

• redirect overview

            || 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

• or

  $ 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

• marslo/mytools reference:

• ldapsearch Examples

• The ldapsearch Tool

• Querying AD with ldapsearch

-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 = [e-mail]
  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

• install

  $ sudo update-alternatives --install /usr/bin/java java /opt/java/jdk1.8.0_121/bin/java 999
  $ sudo update-alternatives --auto java
  $ sudo update-alternatives --install /usr/bin/javac javac /opt/java/jdk1.8.0_121/bin/javac 999
  $ sudo update-alternatives --auto javac

• modify

  $ ls -altrh $(which -a nc)
  lrwxrwxrwx 1 root root 22 Jun  1 04:02 /usr/bin/nc -> /etc/alternatives/nmap
  
  $ sudo alternatives --config nmap
  There are 2 programs which provide 'nmap'.
  
    Selection    Command
  -----------------------------------------------
  *+ 1           /usr/bin/netcat
     2           /usr/bin/ncat
  
  Enter to keep the current selection[+], or type selection number: 1

polar clock

polar clock

take screenshots of websites from terminal

[!NOTE|label:references:]

• capture-website-cli | pageres-cli | break-shot

• Take screenshots of websites from terminal

• Scrot: Linux command-line screen grabs made simple

• firefox

  $ firefox -screenshot http://example.com