UnixCommand/CoreUtils 

The content are copied from Gnu Info pages:

• cat invocation:: Concatenate and write files.
• tac invocation:: Concatenate and write files in reverse.
• nl invocation:: Number lines and write files.
• od invocation:: Write files in octal or other format

• fmt invocation:: Reformat paragraph text.
• pr invocation:: Paginate or columnate files for printing.
• fold invocation:: Wrap input lines to fit in specified width

• head invocation:: Output the first part of files.
• tail invocation:: Output the last part of files.
• split invocation:: Split a file into fixed-size pieces.
• csplit invocation:: Split a file into context-determined pieces.

• wc invocation:: Print newline, word, and byte counts.
• sum invocation:: Print checksum and block counts.
• cksum invocation:: Print CRC checksum and byte counts.
• md5sum invocation:: Print or check message-digests.

• sort invocation:: Sort text files.
• uniq invocation:: Uniquify files.
• comm invocation:: Compare two sorted files line by line.
• ptx invocation:: Produce a permuted index of file contents.
• tsort invocation:: Topological sort.
• tsort background:: Where tsort came from.

• cut invocation:: Print selected parts of lines.
• paste invocation:: Merge lines of files.
• join invocation:: Join lines on a common field.

• tr invocation:: Translate, squeeze, and/or delete characters.
• expand invocation:: Convert tabs to spaces.
• unexpand invocation:: Convert spaces to tabs

• ls invocation:: List directory contents.
• dir invocation:: Briefly ls.
• vdir invocation:: Verbosely ls.
• dircolors invocation:: Color setup for ls, etc

• cp invocation:: Copy files.
• dd invocation:: Convert and copy a file.
• install invocation:: Copy files and set attributes.
• mv invocation:: Move (rename) files.
• rm invocation:: Remove files or directories.
• shred invocation:: Remove files more securely.

• link invocation:: Make a hard link via the link syscall
• ln invocation:: Make links between files.
• mkdir invocation:: Make directories.
• mkfifo invocation:: Make FIFOs (named pipes).
• mknod invocation:: Make block or character special files.
• readlink invocation:: Print the referent of a symbolic link.
• rmdir invocation:: Remove empty directories.
• unlink invocation:: Remove files via the unlink syscall

• chgrp invocation:: Change file groups.
• chmod invocation:: Change access permissions.
• chown invocation:: Change file owners and groups.
• touch invocation:: Change file timestamps.

• df invocation:: Report file system disk space usage.
• du invocation:: Estimate file space usage.
• stat invocation:: Report file or file system status.
• sync invocation:: Synchronize memory and disk.

• echo invocation:: Print a line of text.
• printf invocation:: Format and print data.
• yes invocation:: Print a string until interrupted.

• false invocation:: Do nothing, unsuccessfully.
• true invocation:: Do nothing, successfully.
• test invocation:: Check file types and compare values.
• expr invocation:: Evaluate expressions.

• tee invocation:: Redirect output to multiple files.

• basename invocation:: Strip directory and suffix from a file name.
• dirname invocation:: Strip non-directory suffix from a file name.
• pathchk invocation:: Check file name portability.

• pwd invocation:: Print working directory.
• stty invocation:: Print or change terminal characteristics.
• printenv invocation:: Print environment variables.
• tty invocation:: Print file name of terminal on standard inp

• id invocation:: Print user identity.
• logname invocation:: Print current login name.
• whoami invocation:: Print effective user ID.
• groups invocation:: Print group names a user is in.
• users invocation:: Print login names of users currently logged in.
• who invocation:: Print who is currently logged in.

• date invocation:: Print or set system date and time.
• uname invocation:: Print system information.
• hostname invocation:: Print or set system name.
• hostid invocation:: Print numeric host identifier.

• chroot invocation:: Modify the root directory.
• env invocation:: Modify environment variables.
• nice invocation:: Modify niceness.
• nohup invocation:: Immunize to hangups.
• su invocation:: Modify user and group ID.

• kill invocation:: Sending a signal to processes

• sleep invocation:: Delay for a specified time.

• factor invocation:: Show factors of numbers.
• seq invocation:: Print sequences of numbers.