Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Simple file encryption with OpenSSL
Answer:
You have a single file (input.txt), and you want to encrypt it with a password, it is easy with OpenSSL.
# openssl aes-128-cbc -salt -in input.txt-out input.aes
Enter the password twice.
When you want to decrypt it, use the command.
# openssl aes-128-cbc -d -salt -in input.aes -out output.txt
Case conversion of string in Linux
Answer:
To convert a string to upper case letter, you can use the following command.
# echo 'Test' | tr '[:lower:]' '[:upper:]'
On the other hand, if you want to convert from upper case to lower case, you can use
#echo 'Test' | tr '[:upper:]' '[:lower:]'
How to validate the format of a XML file in Linux?
Answer:
You can use xmllint, which came as part of the libxml2-utils package.
To install
# sudo apt-get install libxml2-utils
To validate the format of XML document
# xmllint --noout file.xml
Specify a port with the scp command
Answer:
If you want to use scp to copy file to remote machine, but that ssh server is listening at port other than 22, you can use the following command syntax.
# scp -P 6000 test.txt john@remoteserver:/home/john/
Please notes it is -P, not -p.
Create ISO image from CD-ROM in Linux
Answer:
1. Put the CD in your CDROM
2. umount the CD if it was mounted automatically (assume the current mount point is at /mnt/cdrom, you can type the mount command to check if your are not sure)
# umount /mnt/cdrom
3. Create the ISO image
# dd if=/dev/cdrom of=/tmp/cd.iso
