flc · May 25, 2022 14:20 · Nov 1, 2021 · Apr 22, 2021 · Apr 21, 2021 · Apr 13, 2021
diff --git a/commands.txt b/commands.txt
@@ -178,3 +178,6 @@ openssl s_client -connect example.com:443 -tls1_3
 
 # list all the processes currently listening
 ss -ltup
+
+# delete files older than 180 days in the current directory tree
+find . -type f -mtime +180 | xargs rm
diff --git a/commands.txt b/commands.txt
@@ -175,3 +175,6 @@ openssl s_client -connect example.com:443 -tls1_1
 openssl s_client -connect example.com:443 -tls1_2
 # TLS1.3
 openssl s_client -connect example.com:443 -tls1_3
+
+# list all the processes currently listening
+ss -ltup
diff --git a/commands.txt b/commands.txt
@@ -166,4 +166,12 @@ sudo lsof -i -P -n | grep LISTEN
 
 # git | delete all local branches that are gone
 # will not delete branches that are not fully merged
-git branch -vv | grep gone | cut -d " " -f3 | xargs git branch -d
+git branch -vv | grep gone | cut -d " " -f3 | xargs git branch -d
+
+# check TLS connections
+# TLS1.1
+openssl s_client -connect example.com:443 -tls1_1
+# TLS1.2
+openssl s_client -connect example.com:443 -tls1_2
+# TLS1.3
+openssl s_client -connect example.com:443 -tls1_3
diff --git a/commands.txt b/commands.txt
@@ -165,5 +165,5 @@ ssh-keygen -t rsa -b 4096 -C "<optional_comment>"
 sudo lsof -i -P -n | grep LISTEN
 
 # git | delete all local branches that are gone
-# will not delete branches that are nto fully merged
+# will not delete branches that are not fully merged
 git branch -vv | grep gone | cut -d " " -f3 | xargs git branch -d
diff --git a/commands.txt b/commands.txt
@@ -100,6 +100,7 @@ tail -n +2 file.csv | awk -F "," '$2 >= <my threshold value>' | wc -l
 
 # pg_dump ssh tunnel
 ssh -o "Compression=no" mydbserver "pg_dump -Fc -Z9 -U postgres mydb" > mydb.dump
+ssh -i <private_key_path> -o "Compression=no" yourdomain.com "pg_dump --username=<username> --host=localhost --blobs --verbose --format=c --compress=9 <db_name>" > mydb.dump
 
 # generate random password
 # of course there are tons of ways to do this

diff --git a/commands.txt b/commands.txt
@@ -161,4 +161,8 @@ cat -A file
 ssh-keygen -t rsa -b 4096 -C "<optional_comment>"
 
 # check listening ports and applications
-sudo lsof -i -P -n | grep LISTEN
+sudo lsof -i -P -n | grep LISTEN
+
+# git | delete all local branches that are gone
+# will not delete branches that are nto fully merged
+git branch -vv | grep gone | cut -d " " -f3 | xargs git branch -d
diff --git a/commands.txt b/commands.txt
@@ -158,4 +158,7 @@ sed -e "s/\r//g" file > newfile
 cat -A file
 
 # generate ssh key
-ssh-keygen -t rsa -b 4096 -C "<optional_comment>"
+ssh-keygen -t rsa -b 4096 -C "<optional_comment>"
+
+# check listening ports and applications
+sudo lsof -i -P -n | grep LISTEN
diff --git a/commands.txt b/commands.txt
@@ -125,7 +125,7 @@ openssl enc -aes-256-cbc -md sha512 -pbkdf2 -iter 1000 -salt -in <file> -out <en
 openssl aes-256-cbc -d -md sha512 -pbkdf2 -iter 1000 -in <encrypted_file> -out <file> -k <passphrase>
 
 # generate your dhparam.pem file
-openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
+openssl dhparam -out /etc/nginx/ssl/dhparam.pem 4096
 
 # search for pattern in codebase
 grep -inIEr --color=ALWAYS "<pattern_to_search>" .

diff --git a/commands.txt b/commands.txt
@@ -155,4 +155,7 @@ sed -i -e '$a\' file
 sed -e "s/\r//g" file > newfile
 
 # check for all visible characters
-cat -A file
+cat -A file
+
+# generate ssh key
+ssh-keygen -t rsa -b 4096 -C "<optional_comment>"
diff --git a/commands.txt b/commands.txt
@@ -13,6 +13,9 @@ tail -n +2 file > new_file
 # remove first line of the file (less efficient)
 sed 1d file > newfile
 
+# show from a specific line number <number> till the end of the file
+tail -n +<number> file
+
 # count how many lines of a file contain a pattern
 cat file | grep pattern | wc -l
 grep pattern -c file

diff --git a/commands.txt b/commands.txt
@@ -43,6 +43,12 @@ tar -xzf archive.tar.gz
 # view an tar archive
 tar tvf archive.tar.gz
 
+# create uncompressed tar archive
+tar -cvf archive.tar dirname
+
+# extract uncompressed tar archive
+tar -xvf archive.tar dirname
+
 # extract tar.bz2
 tar jxf filename.tar.bz2
 

diff --git a/commands.txt b/commands.txt
@@ -140,4 +140,10 @@ rsync -avz -e "ssh -i <ssh_key_path> -o StrictHostKeyChecking=no -o UserKnownHos
 find . -type f | wc -l
 
 # adds newline at the end of the file if it doesn't already end with a newline
-sed -i -e '$a\' file
+sed -i -e '$a\' file
+
+# remove CTRL-M (^M) characters from a file
+sed -e "s/\r//g" file > newfile
+
+# check for all visible characters
+cat -A file
diff --git a/commands.txt b/commands.txt
@@ -121,7 +121,7 @@ openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
 # search for pattern in codebase
 grep -inIEr --color=ALWAYS "<pattern_to_search>" .
 
-# searcg for pattern in files with specific extension (.py in the example)
+# search for pattern in files with specific extension (.py in the example)
 find . -iname '*.py' | xargs grep -inIE --color=ALWAYS "<pattern_to_search>"
 
 # copy directory tree recursively without overwrite

diff --git a/commands.txt b/commands.txt
@@ -121,6 +121,9 @@ openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
 # search for pattern in codebase
 grep -inIEr --color=ALWAYS "<pattern_to_search>" .
 
+# searcg for pattern in files with specific extension (.py in the example)
+find . -iname '*.py' | xargs grep -inIE --color=ALWAYS "<pattern_to_search>"
+
 # copy directory tree recursively without overwrite
 rsync -a -v --ignore-existing <src_dir> <dst_dir>
 

diff --git a/commands.txt b/commands.txt
@@ -111,6 +111,10 @@ sudo reboot
 openssl aes-256-cbc -salt -in <file> -out <encrypted_file> -k <passphrase>
 openssl aes-256-cbc -d -in <encrypted_file> -out <file> -k <passphrase>
 
+# encrypt/decrypt file with openssl NEW
+openssl enc -aes-256-cbc -md sha512 -pbkdf2 -iter 1000 -salt -in <file> -out <encrypted_file> -k <passphrase>
+openssl aes-256-cbc -d -md sha512 -pbkdf2 -iter 1000 -in <encrypted_file> -out <file> -k <passphrase>
+
 # generate your dhparam.pem file
 openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
 

diff --git a/commands.txt b/commands.txt
@@ -104,6 +104,9 @@ sudo chage -d 0 <username>
 sudo shutdown -h now
 sudo poweroff
 
+# server restart / reboot
+sudo reboot
+
 # encrypt/decrypt file with openssl
 openssl aes-256-cbc -salt -in <file> -out <encrypted_file> -k <passphrase>
 openssl aes-256-cbc -d -in <encrypted_file> -out <file> -k <passphrase>

diff --git a/commands.txt b/commands.txt
@@ -127,4 +127,7 @@ lsof -Fpcn | nawk '/^p/ { pid=substr($0,2) } /^c/ { cmd=substr($0,2) } /^n/ { fd
 rsync -avz -e "ssh -i <ssh_key_path> -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" --progress <file> <username>@<remote_ip>:<remote_dir>
 
 # count files in a directory recursively
-find . -type f | wc -l
+find . -type f | wc -l
+
+# adds newline at the end of the file if it doesn't already end with a newline
+sed -i -e '$a\' file
diff --git a/commands.txt b/commands.txt
@@ -124,4 +124,7 @@ ps -e -orss,%mem,cputime,%cpu,pid,args | sort -b -k1,1n | pr -TW$COLUMNS
 lsof -Fpcn | nawk '/^p/ { pid=substr($0,2) } /^c/ { cmd=substr($0,2) } /^n/ { fd[cmd"["pid"]"]++ } END  { for (cc in fd) printf("%-30s %i\n",cc,fd[cc]) } ' | sort -n -k 2 | tail -30
 
 # copy file with rsync over SSH 
-rsync -avz -e "ssh -i <ssh_key_path> -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" --progress <file> <username>@<remote_ip>:<remote_dir>
+rsync -avz -e "ssh -i <ssh_key_path> -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" --progress <file> <username>@<remote_ip>:<remote_dir>
+
+# count files in a directory recursively
+find . -type f | wc -l
diff --git a/commands.txt b/commands.txt
@@ -122,3 +122,6 @@ ps -e -orss,%mem,cputime,%cpu,pid,args | sort -b -k1,1n | pr -TW$COLUMNS
 
 # find processes with maximum file descriptors
 lsof -Fpcn | nawk '/^p/ { pid=substr($0,2) } /^c/ { cmd=substr($0,2) } /^n/ { fd[cmd"["pid"]"]++ } END  { for (cc in fd) printf("%-30s %i\n",cc,fd[cc]) } ' | sort -n -k 2 | tail -30
+
+# copy file with rsync over SSH 
+rsync -avz -e "ssh -i <ssh_key_path> -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" --progress <file> <username>@<remote_ip>:<remote_dir>
diff --git a/commands.txt b/commands.txt
@@ -115,4 +115,10 @@ openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
 grep -inIEr --color=ALWAYS "<pattern_to_search>" .
 
 # copy directory tree recursively without overwrite
-rsync -a -v --ignore-existing <src_dir> <dst_dir>
+rsync -a -v --ignore-existing <src_dir> <dst_dir>
+
+# find processes with most memory usage
+ps -e -orss,%mem,cputime,%cpu,pid,args | sort -b -k1,1n | pr -TW$COLUMNS
+
+# find processes with maximum file descriptors
+lsof -Fpcn | nawk '/^p/ { pid=substr($0,2) } /^c/ { cmd=substr($0,2) } /^n/ { fd[cmd"["pid"]"]++ } END  { for (cc in fd) printf("%-30s %i\n",cc,fd[cc]) } ' | sort -n -k 2 | tail -30
diff --git a/commands.txt b/commands.txt
@@ -112,4 +112,7 @@ openssl aes-256-cbc -d -in <encrypted_file> -out <file> -k <passphrase>
 openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
 
 # search for pattern in codebase
-grep -inIEr --color=ALWAYS "<pattern_to_search>" .
+grep -inIEr --color=ALWAYS "<pattern_to_search>" .
+
+# copy directory tree recursively without overwrite
+rsync -a -v --ignore-existing <src_dir> <dst_dir>
diff --git a/commands.txt b/commands.txt
@@ -109,4 +109,7 @@ openssl aes-256-cbc -salt -in <file> -out <encrypted_file> -k <passphrase>
 openssl aes-256-cbc -d -in <encrypted_file> -out <file> -k <passphrase>
 
 # generate your dhparam.pem file
-openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
+openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
+
+# search for pattern in codebase
+grep -inIEr --color=ALWAYS "<pattern_to_search>" .
diff --git a/commands.txt b/commands.txt
@@ -107,3 +107,6 @@ sudo poweroff
 # encrypt/decrypt file with openssl
 openssl aes-256-cbc -salt -in <file> -out <encrypted_file> -k <passphrase>
 openssl aes-256-cbc -d -in <encrypted_file> -out <file> -k <passphrase>
+
+# generate your dhparam.pem file
+openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
diff --git a/commands.txt b/commands.txt
@@ -102,4 +102,8 @@ sudo chage -d 0 <username>
 
 # server shutdown
 sudo shutdown -h now
-sudo poweroff
+sudo poweroff
+
+# encrypt/decrypt file with openssl
+openssl aes-256-cbc -salt -in <file> -out <encrypted_file> -k <passphrase>
+openssl aes-256-cbc -d -in <encrypted_file> -out <file> -k <passphrase>
diff --git a/commands.txt b/commands.txt
@@ -98,4 +98,8 @@ ssh -o "Compression=no" mydbserver "pg_dump -Fc -Z9 -U postgres mydb" > mydb.dum
 < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-32};echo;
 
 # force the user to change their password upon next login
-sudo chage -d 0 <username>
+sudo chage -d 0 <username>
+
+# server shutdown
+sudo shutdown -h now
+sudo poweroff
diff --git a/commands.txt b/commands.txt
@@ -96,3 +96,6 @@ ssh -o "Compression=no" mydbserver "pg_dump -Fc -Z9 -U postgres mydb" > mydb.dum
 # of course there are tons of ways to do this
 # you can replace 32 with the desired password length
 < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-32};echo;
+
+# force the user to change their password upon next login
+sudo chage -d 0 <username>
diff --git a/commands.txt b/commands.txt
@@ -90,4 +90,9 @@ sudo renice -n <niceness> -g <pid>
 tail -n +2 file.csv | awk -F "," '$2 >= <my threshold value>' | wc -l
 
 # pg_dump ssh tunnel
-ssh -o "Compression=no" mydbserver "pg_dump -Fc -Z9 -U postgres mydb" > mydb.dump
+ssh -o "Compression=no" mydbserver "pg_dump -Fc -Z9 -U postgres mydb" > mydb.dump
+
+# generate random password
+# of course there are tons of ways to do this
+# you can replace 32 with the desired password length
+< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-32};echo;
diff --git a/commands.txt b/commands.txt
@@ -55,7 +55,7 @@ sudo groupadd <groupname>
 # add existing user to group
 sudo usermod -a -G <groupname> <username>
 
-# ass a user to multiple groups
+# add a user to multiple groups
 sudo usermod -a -G <groupname1>,<groupname2>,<groupname3> <username>
 
 # view user's group assignemnts

diff --git a/commands.txt b/commands.txt
@@ -62,6 +62,14 @@ sudo usermod -a -G <groupname1>,<groupname2>,<groupname3> <username>
 id <username>
 groups <username>
 
+# make a directory accessible for a group
+# change group of all files/directories recursively
+sudo chgrp -R <groupname> <directory>
+# add write permissions to group
+sudo chmod -R g+w <directory>
+# set "GID", so that all new files and directories created under <directory> are owned by the group
+sudo find <directory> -type d -exec chmod 2775 {} \;
+
 # randomize lines of a big file memory efficiently
 uuid -v 4 -n $(wc -l < lines.txt) | paste - lines.txt | sort | cut -f2 > lines_random.txt 
 

diff --git a/commands.txt b/commands.txt
@@ -47,7 +47,20 @@ tar tvf archive.tar.gz
 tar jxf filename.tar.bz2
 
 # add user
-sudo adduser username
+sudo adduser <username>
+
+# add group
+sudo groupadd <groupname>
+
+# add existing user to group
+sudo usermod -a -G <groupname> <username>
+
+# ass a user to multiple groups
+sudo usermod -a -G <groupname1>,<groupname2>,<groupname3> <username>
+
+# view user's group assignemnts
+id <username>
+groups <username>
 
 # randomize lines of a big file memory efficiently
 uuid -v 4 -n $(wc -l < lines.txt) | paste - lines.txt | sort | cut -f2 > lines_random.txt