Ubuntu – useradd: cannot lock /etc/passwd; try again later

It's not recommended to manually modify /etc/passwd, /etc/shadow, /etc/group or /etc/gshadow because the risk of breakage. If you're looking for an alternative command that is easier to use, take a look at adduser(8). All you have to run is:

sudo adduser user

The shell will be /bin/bash by default per /etc/adduser.conf.

Usually, if you wish to add a user with the bash shell, thereby create a home directory /home/user and a user group, you would use:

sudo useradd --create-home --shell /bin/bash --user-group user

This command is basically determining a free User ID $UID and Group ID $GID and then executing the next commands:

echo "user:x:$UID:$GID::/home/user:/bin/bash" | sudo tee -a /etc/passwd
echo "user:x:$GID:" | sudo tee -a /etc/group
echo "user:!:$DATE_OF_LAST_PASS_CHANGE:0:99999:7:::" | sudo tee -a /etc/shadow
echo "user:!::" | sudo tee -a /etc/gshadow

..and thereby possibly making a backup of the files.

The next manual pages about the file formats may be of interest to you:

• passwd(5)
• group(5)
• shadow(5)
• gshadow(5)

Read man 1 login, read /etc/login.defs. Also see what you have in $PATH, $LOGNAME.

I'd make sure that /home/glperez really exists, with ls -ld /home/glperez. If it does not exist, and /etc/login.defs permits, you will be given a directory that login is sure exists, /.

You can also check that /bin/bash exists, is executable, and is included in /etc/shells

ls  -l /bin/bash;ldd /bin/bash;grep /bin/bash /etc/shells  

You should ask blackhawk2's sysadm how s/he created the glperez account. useradd or adduser? What parameters? Are you supposed to have an encrypted home directory? Does blackhawk2 authenticate users locally, or over the network (check /etc/nsswitch.conf)? If over the network, what does that server think of you?