My Notes

Notes on macOS

• Shell
  • Find files
• Tools
  • awk
  • Logging
  • Convert between file formats
  • Scriptable Image Processing System (sips)
  • IP
  • Flush DNS Cache
  • Empty Trash forcefully
  • Disk utitlity
  • nslookup
  • Domain information
  • lsof
• Terminal Commands
  • Shortcuts
• Disk Management
  • File sharing to Ubuntu

Shell

change the shell to zsh

chsh -s /bin/zsh

Edit a file in a TextEdit

open -a TextEdit ~/.zshrc

Find files

Find the file names only with the text recusively

grep -il -r --include "*.py" 'text' .

Find all the files with wild card recursively:

find . -name "*.pyc" -exec ls {} \;

Another recursive example with include and exclude directory:

grep -rI --include='*.py'  --exclude-dir='lib' "S3Service" *

To show all the CHAPTERS:

grep -i chapter novel.txt

Cut only the chapter headings

grep -i chapter novel.txt | cut -d' ' -f3-

Read the line where CHAPTER contains but start with ‘the’ in the novel.txt.

grep -E '^CHAPTER (.*)\. The' novel.txt

Every word more 5 or more characters

grep -oE '\w{5,}' novel.txt

In the redhat to start the firewall GUI, type the following command:

sudo system-config-firewall

Here the way to validate xml file for schema and generate the report

	xmllint  --noout --valid --schema UserCentralClients.xsd sample2.xml > error.txt 2>&1

noout will stop xml written to the error.txt.

Tools

Here some important tools to use in the shell.

awk

Commandline

awk -F, '{$2="***"; print $1 $2}'  test.txt

Above logic in the file called f:

awk -F, -f t test.txt 

Both the above commands produce the same.

here the contents of the f file:

BEGIN {
  print "1 st \t 2nd"
  print "==== \t ==="
}

{
  $2="***";
  print $1 "\t" $2
}

END{
  print "the end"
}

Logging

For the log stream

log stream

To filter

log stream --predicate 'eventMessage contains "<searh word>"'

Filter by the specific process:

log stream  --process 153
# or
log stream --predicate '(process == <PID>)'

Convert between file formats

To convert files:

textutil -convert doc textfile.rtf -output msword.doc

Scriptable Image Processing System (sips)

To make the jpeg to 200 pixels wide

sips --resampleWidth 200 image_file.jpeg

IP

To get current public IPv4 address:

curl -4 https://icanhazip.com/; echo

Flush DNS Cache

To reset the DNS cache

sudo killall -HUP mDNSResponder

You have to provide root password.

Empty Trash forcefully

Sometime it is not possible to empty the trash. Run the following command:

sudo rm -ri ~/.Trash/*

Disk utitlity

diskutil list

nslookup

In addition to showing you a host’s domain name or IP address, nslookup gives you the IP address of the DNS server i if you’re trying to diagnose a DNS problem:

nslookup ojitha.blogspot.com
nslookup ojitha.github.io

Domain information

Find out what person or organization owns a domain name

whois ojitha.blogspot.com

lsof

Which apps have open TCP network connections:

lsof -i

###

Terminal Commands

Find the hidden files

defaults write com.apple.finder AppleShowAllFiles true; killall Finder

Change the screenshot format (bmp,gif,pdf,png,tiff or jpeg)

defaults write com.apple.screencapture type -string "jpeg"; killall SystemUIServer

Software updates CLI:

sudo softwareupdate -i -a

Here, -i and -a flags to go ahead and install every available update.

To list the last reboots:

last reboot

Find the uptime:

uptime

History of user Loggins:

last

To add the new user

sysadminctl -addUser <username> -fullName "<Full Name>" -password <password>

To change the password of the user:

sysadminctl -resetPasswordFor <username> -newPassword <new password> -passwordHint "<password hint>"

Find the type of the command

type -a pwd

create tar file

tar -czvf mylogs.tar.gz logs-*.log

find the directory in the Unix

find / -type d -name 'pyve*' 2>&1 | grep -v "Permission denied"
#or
find . -type d -name 'pyve*'  2>/dev/null

filter the file lines:

sed -n '1 , 3 p' my.txt > test.txt

Top occurrence words in a page

curl -s http://www.gutenberg.org/files/4300/4300-0.txt | tr '[:upper:]' '[:lower:]' | grep -oE '\w+' | sort | uniq -c | sort -nr | head -n 10

Use of Python as command line tool

#!/usr/bin/env python
from sys import stdin, stdout
while True:
    line = stdin.readline()
    if not line:
        break
    stdout.write("%d\n" % int(line))
    stdout.flush()

Above will display the lines generated from the sequence.

#permission
chmod u+x stream.py

#create the pipeline
seq 1000 | ./stream.py

Substitute seq

seq -f "Line %g" 10

Here the equlents, lines is a file

< lines head -n 3
< lines sed -n 1,3p
< lines awk 'NR<=3'

Shortcuts

If you want to select all and only the output from the most recent command press ⌘-Shift-A.

Disk Management

To display size of the folder

du -hsx *

this will display the usage of the directory. The following code show the top 20 files which used most of the file space

du -a | sort -n -r | head -n 20

This will show directory wise usage of file space

du -hsx * | sort -n -r | head -n 20

Here

• du command -h option : display sizes in human readable format.
• du command -s option : show only a total for each argument (summary).
• du command -x option : skip directories on different file systems.

Enable Clipboard reddit

1.Run Terminal

2.Type the following to check to see if ClipboardSharingEnabled is equal to zero. (if so, proceed to #3)

defaults read ~/Library/Preferences com.apple.coreservices.useractivityd.plist

3.Type the following to delete the ClipboardSharingEnabled = 0 setting.

defaults delete ~/Library/Preferences/com.apple.coreservices.useractivityd.plist ClipboardSharingEnabled

4.Reboot your mac. Copy paste across devices should now work.

Alternatively, type the following to enable ClipboardSharingEnabled as the default:

defaults write ~/Library/Preferences/com.apple.coreservices.useractivityd.plist ClipboardSharingEnabled 1

File sharing to Ubuntu

First enable the sharing in the Mac as explained in the Set up file sharing on Mac.

In the Ubuntu you can access this as follows