diff --git a/README.md b/README.md
index 52175e8..2671180 100644
--- a/README.md
+++ b/README.md
@@ -309,6 +309,7 @@ disown -a && exit
 
 ```bash
 kill -9 $$
+unset HISTFILE && exit
 ```
 
 ###### Perform a branching conditional
@@ -371,6 +372,13 @@ rename 'y/A-Z/a-z/' *
 printf "%`tput cols`s" | tr ' ' '#'
 ```
 
+###### Show shell history without line numbers
+
+```bash
+history | cut -c 8-
+fc -l -n 1 | sed 's/^\s*//'
+```
+
 ___
 
 ##### Tool: [mount](https://en.wikipedia.org/wiki/Mount_(Unix))
@@ -438,6 +446,38 @@ find / -type f -size +20M
 find -type f -exec md5sum '{}' ';' | sort | uniq --all-repeated=separate -w 33
 ```
 
+###### Change permission only for files
+
+```bash
+cd /var/www/site && find . -type f -exec chmod 766 {} \;
+cd /var/www/site && find . -type f -exec chmod 664 {} +
+```
+
+###### Change permission only for directories
+
+```bash
+cd /var/www/site && find . -type d -exec chmod g+x {} \;
+cd /var/www/site && find . -type d -exec chmod g+rwx {} +
+```
+
+###### Find files and directories for specific user
+
+```bash
+find . -user <username> -print
+```
+
+###### Find files and directories for all without specific user
+
+```bash
+find . \!-user <username> -print
+```
+
+###### Delete older files than 60 days
+
+```bash
+find . -type f -mtime +60 -delete
+```
+
 ___
 
 ##### Tool: [top](https://en.wikipedia.org/wiki/Top_(software))
@@ -656,6 +696,20 @@ EOF
 ))
 ```
 
+###### Convert DER to PEM
+
+```bash
+( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \
+openssl x509 -in ${_fd_der} -inform der -outform pem -out ${_fd_pem} )
+```
+
+###### Convert PEM to DER
+
+```bash
+( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \
+openssl x509 -in ${_fd_pem} -outform der -out ${_fd_der} )
+```
+
 ###### Checking whether the private key and the certificate match
 
 ```bash
@@ -1201,3 +1255,15 @@ grep . filename > newfilename
 ```bash
 grep -vE '(error|critical|warning)' filename
 ```
+
+###### Show data from file without comments
+
+```bash
+grep -v ^[[:space:]]*# filename
+```
+
+###### Show data from file without comments and new lines
+
+```bash
+egrep -v '#|^$' filename
+```