A Linux Commands Overview

Some useful terminal commands in Linux or OSX

-> List all cronjobs from all users and services (all existing)

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for user in $(cut -f1 d: /etc/passwd); do crontab -u $user -l; done

-> For all users and services in /etc/passwd

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for user in $(cut -f1 -d: /etc/passwd); do echo $user; crontab -u $user -l; done

-> A nicer list for each user in /etc/passwd

-> Find and delete 10 days old files in /tmp

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find /tmp -ctime +10 -exec rm -rf {} +

-> Zip and Tar over SSH compression

Compresses/packs the archiveName from any directory or file to a new file

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# dir with zip (you might need to install this)
zip -r archiveName.zip /directory/to/compress
# decompress (extracts archiveName's content to the current folder (in place))
unzip archiveName.zip

# dir with tar
tar -cvf archive_name.tar /directory/to/compress
# decompress (extracts archiveName's content to the folder '/tmp')
tar -xvf archiveName.tar -C /tmp

# dir with tar and gzip compression
tar -czvf archiveName.tar.gz /path/to/dirOrFile
# decompress (extracts archiveName's content to the folder '/tmp')
tar -xzvf archiveName.tar.gz -C /tmp

# dir with tar and bzip2 compression
tar -jcvf archiveName.tar.bz2 /directory/to/compress
# decompress (extracts archiveName's content to the folder '/tmp')
tar -jzvf archiveName.tar.bz2 -C /tmp

-> Shop open ports

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netstat -lntp

-> Show usage of port $NUMBER

here TCP protocol with port 9000

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lsof -nP -i4TCP:9000 |grep LISTEN

-> Search | Find files

Where you are

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find -name "*nginx*"

Or in a different, named folder

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find /var/log -name "*nginx*"

-> Chmod - Change permissions

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d rwx r-x r-x 6 User staff 204 17 Mai 15:30 vendor
^ ^^^ ^^^^----^^^^^
| ||| |||| ||||| 
| ||| -> belongs to "User" in the user-group "staff"
| ||| | || -> right to execute
| || | | -> right to write
| | | -> right to read
| -> directory

actually change:

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chmod [-v] [-R [-L | -P]] mode file ...
  verbose
    recursive
      [-L: symbolic links are followed]
      [-P: don't follow symbolic links (default)]

Overview for modes / bitmatrix:

inputvalue	bitwise	shownrights	meaning
0	000	—	no access
1	001	–x	execute
2	010	-w-	write
3	011	-wx	write / execute
4	100	r–	read
5	101	r-x	read / execute
6	110	rw-	read / write
7	111	rwx	read / write / execute

Now set all files inside this folder to d - rwx r-x r--:

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user@computer $ chmod -R 754 vendor/

-> Chown - Change file | folder ownage

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drwxr-xr-x 3 root staff 102 25 Mai 2016 .vim
^^^^--^^^^^ |||| |||||
             -> belongs to user "root" in the user-group "staff"

Syntax for change-ownage ‘chown’:

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chown [-v] [-R [-L | -P]] owner[:group] file ...
- See 'chown' above for declaration of arguments,
- owner means the users account name
- group is optional and means the name of 'his' user group

Now I want to change this belonging recursively to me, user:staff (with user’s group!):

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User@computer /folder/where/vim/is $ su (or) sudo su 
root@computer / # cd /folder/where/vim/is 
root@computer /folder/where/vim/is # chown -R user:staff .vim 
root@computer /folder/where/vim/is # [CTRL+D] 
User@computer /folder/where/vim/is $ exit

#How-To #Linux