JCAC Mod 5 Advanced UNIX Commands

touch: Creates an empty file and is also used to modify a files timestamp
touch -t: Manipulates the file’s access date/time stamp

Creates one or more directories
Creates a directory where no parent exists (nested)

Copies files and directories
Recursively copy directories.

Moves or renames files and directories

Creates a link between files or directories
Creates a symbolic link to another file.

Removes a file or a directory with contents if using the -r option
rm -f : Ignore nonexistent files, never prompt (force).

Searches a file or files for lines that contain strings of a certain pattern.

Locates files having certain specified characteristics

Displays full path (location) of most (shell) commands

Determines file type.

Displays a snapshot status of active processes. (A process running in the background is called a daemon )
ps -e: Lists information about every process running
ps -l: Displays in a long format
ps -f: Generates a list in full mode format

Stops a process from running using its PID
Used to kill a stubborn process that won’t die

Stops a process from running using its process name
Used to kill a stubborn process that won’t die.
-HUP: Used to immediately re-spawn a process to effect configuration changes. After modifying a daemon’s configuration file, use pkill -HUP to hang up and restart the daemon with the new configuration

Maintains a history file of all commands run by a particular user in that shell.

Prints the strings of printable characters in a file (not ASCII characters). Useful in determining content of non-text files (executables)

Creates a typescript of the terminal session (everything printed on the terminal). CTRL+d ends the script session. View results using less.

Used to switch from the current user account to another. It is often used to switch to root user to perform tasks requiring elevated privileges.

Displays who the user is logged in as at this moment (after switching user).

Displays user login information including login name, time, terminal, and more

Displays information about the user(s) logged in and what they are doing.

Compresses a files and appends a .gz file extension. The original file is replaced

Decompresses a file that was compressed with gzip

Tape archive utility used to archive files to tape or disk

Create an archive

List table of contents of tar file

Extract, must be in target directory to extract

Compress the archived file using gzip (tarball)

Verbose, list each file as tar reads/writes

Read/write to or from a file

Change to directory

Schedules a job/process for a one-time execution

Lists user’s pending jobs.

Deletes user’s jobs identified by job number

Schedules periodic jobs. The cron daemon (crond) checks the /etc/crontab every minute for any jobs that need to run. To create a cron job, the cron table (crontab) is created or modified.

Edit the crontab

List crontab entries

Creates a new user or updates default new user information

Specifies the path of the user’s home directory;
Linux - users’ home directories are in /home

Makes a home directory if it doesn’t already exist

Assigns whatever group is in default

Deletes a user account
Removes the home directory for specified user

Enables a user to change their password (no user name) or for root to set and modify password settings.