Learn to print the lines of text in a file in reverse order.
- [Male Narrator] Hi and welcome to the next video…of section four,…printing lines in the reverse order.…In the previous video,…we learned about printing text…between line number and pattern numbers.…In this video, we'll see how to print lines…in the reverse order.…This is a very simple section.…It may not seem very useful,…but it can be used to emulate the stacked data…of structure in bash.…This is something interesting.…Let's print the lines of a text file in reverse order.…A little hack with awk can do the task.…However, there is a direct command, TAC,…to do the same as well.…
TAC is the reverse of CAT.…We will first see how to do this with TAC.…The TAC syntax is as follows.…It can also read from standard in as follows.…In TAC, slash n is the line separator,…but we can also specify our own separator…by using the minus s separator option.…We can do it in awk as follows.…Slash in the shell script…is used to conveniently break a single line command sequence…into multiple lines.…
The awk script is very simple.…We store each of the lines into an associative array…
Released
7/17/2017Note: This course was created by Packt Publishing. We are pleased to host this training in our library.
- Printing in the terminal
- Performing math in the Linux shell
- Getting and setting dates
- Working with functions and arguments
- Reading output
- Making comparisons
- Concatenating text
- Finding, editing, generating, and deleting files
- Running parallel processes
- Using regular expressions
- Downloading webpages
- Parsing data from a website
- Finding broken links
- Backing up and archiving
- Transferring files and data through the network
- Monitoring your Linux system
- Gathering data for system administration
Skill Level Intermediate
Duration
Views
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1. Shell Something Out
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Printing in the terminal6m 4s
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Math with the shell3m 5s
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Visiting aliases2m 25s
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Debugging the script2m 46s
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Functions and arguments4m 31s
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Comparisons and tests6m 22s
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2. Have a Good Command
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Concatenating with cat5m 30s
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Finding files and file listing18m 46s
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Playing with xargs11m 41s
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Translating with tr6m 51s
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Checksum and verification4m 46s
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Splitting files and data4m 53s
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Automating interactive input4m 10s
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3. File In, File Out
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Generating files of any size4m 24s
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Making files immutable2m 13s
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Using loopback files6m 15s
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Printing the directory tree3m 18s
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4. Texting and Driving
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Using regular expressions9m 25s
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5. Tangled Web? Not at All
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Downloading from a web page5m 15s
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A primer on cURL7m 11s
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Image crawler and downloader3m 36s
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Web photo album generator1m 54s
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6. The Backup Plan
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Archiving with tar10m 33s
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Archiving with cpio2m 31s
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Compressing data with gzip5m 27s
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Faster archiving with pbzip23m 15s
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Backup snapshots with rsync6m 55s
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7. The Old-Boy Network
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Let us ping4m 53s
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Creating arbitrary sockets2m 45s
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8. Put on the Monitor's Cap
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Logging with syslogd2m 44s
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Monitoring disk activity1m 41s
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9. Administration Calls
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Gathering system information1m 57s
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Scheduling with cron7m 7s
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User administration script5m 16s
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Video: Printing lines in the reverse order