Viewing text files

$ head

head report.txt
View first 10 lines of the file, report.txt.

head -5 report.txt
View first 5 lines of the file, report.txt.

$ tail

tail weblog
View last 10 lines of the file, weblog.

tail -20 weblog
View last 20 lines of the file, weblog.

$ cat - concatenate

cat /etc/fstab
View all of file /etc/fstab.

cat a.txt b.txt > ab.txt
Append (concatenate) b.txt to a.txt and redirect (>) result to ab.txt.

Intermediate tip:

You can also use cat on files in the /proc directory to display information about your system. For example, cat /proc/modules displays the kernel modules loaded, and cat /proc/pci displays information on your PCI devices. For further details, enter man proc.

$ tac - reverse concatenate

tac log.txt
View all of file log.txt in reverse (last line first to first line last).

$ less

less dirs.txt
View the dirs.txt file in the less program, allowing you to view large files, line by line. (Press q to quit.)

Note:

The more program allows you to view text screen by screen, displaying at the bottom of the screen something like '--More--(86%)' to indicate 86% of the text has been viewed. The less program is the improved more that allows you to scroll up and down, line by line, using the cursor keys.

$ sort

sort list.txt
Display contents of list.txt file in alphabetical order.

sort -r list.txt > sorted_list.txt
Same as above, but in reverse (-r) order, and output result to file, sorted_list.txt.

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