Bash Useful Tricks

-

Source: - bash-shortcuts-for-maximum-productivity Really useful article. Practice until you remember these little tricks. This article will save you a lot of time

Sharing this article on the blog, so that readers can get best tips at one location.

Command Editing Shortcuts

  • Ctrl + a – go to the start of the command line
  • Ctrl + e – go to the end of the command line
  • Ctrl + k – delete from cursor to the end of the command line
  • Ctrl + u – delete from cursor to the start of the command line
  • Ctrl + w – delete from cursor to start of word (i.e. delete backwards one word)
  • Ctrl + y – paste word or text that was cut using one of the deletion shortcuts (such as the one above) after the cursor
  • Ctrl + xx – move between start of command line and current cursor position (and back again)
  • Alt + b – move backward one word (or go to start of word the cursor is currently on)
  • Alt + f – move forward one word (or go to end of word the cursor is currently on)
  • Alt + d – delete to end of word starting at cursor (whole word if cursor is at the beginning of word)
  • Alt + c – capitalize to end of word starting at cursor (whole word if cursor is at the beginning of word)
  • Alt + u – make uppercase from cursor to end of word
  • Alt + l – make lowercase from cursor to end of word
  • Alt + t – swap current word with previous
  • Ctrl + f – move forward one character
  • Ctrl + b – move backward one character
  • Ctrl + d – delete character under the cursor
  • Ctrl + h – delete character before the cursor
  • Ctrl + t – swap character under cursor with the previous one

Command Recall Shortcuts

  • Ctrl + r – search the history backwards
  • Ctrl + g – escape from history searching mode
  • Ctrl + p – previous command in history (i.e. walk back through the command history)
  • Ctrl + n – next command in history (i.e. walk forward through the command history)
  • Alt + . – use the last word of the previous command

Command Control Shortcuts

  • Ctrl + l – clear the screen
  • Ctrl + s – stops the output to the screen (for long running verbose command)
  • Ctrl + q – allow output to the screen (if previously stopped using command above)
  • Ctrl + c – terminate the command
  • Ctrl + z – suspend/stop the command

Bash Bang (!) Commands

Bash also has some handy features that use the ! (bang) to allow you to do some funky stuff with bash commands.
  • !! – run last command
  • !blah – run the most recent command that starts with ‘blah’ (e.g. !ls)
  • !blah:p – print out the command that !blah would run (also adds it as the latest command in the command history)
  • !$ – the last word of the previous command (same as Alt + .)
  • !$:p – print out the word that !$ would substitute
  • !* – the previous command except for the last word (e.g. if you type ‘find some_file.txt /‘, then !* would give you ‘find some_file.txt‘)
  • !*:p – print out what !* would substitute
Variable and their usage in bash script
  • $0 - The name of the Bash script.
  • $1 - $9 - The first 9 arguments to the Bash script. (As mentioned above.)
  • $# - How many arguments were passed to the Bash script.
  • $@ - All the arguments supplied to the Bash script.
  • $? - The exit status of the most recently run process.
  • $$ - The process ID of the current script.
  • $USER - The username of the user running the script.
  • $HOSTNAME - The hostname of the machine the script is running on.
  • $SECONDS - The number of seconds since the script was started.
  • $RANDOM - Returns a different random number each time is it referred to.
  • $LINENO - Returns the current line number in the Bash script.

Comments

Post a Comment

Popular posts from this blog

SOX - Sound eXchange - How to use SOX for audio processing tasks in research.

-
This article is part of the on-going Software for Geeks series. SoX stands for So und e X change. SoX is a cross-platform command line audio utility tool that works on Linux, Windows and MacOS. It is very helpful in the following areas while dealing with audio and music files. Audio File Converter Editing audio files Changing audio attributes Adding audio effects Plus lot of advanced sound manipulation features In general, audio data is described by following four characteristics: Rate – The sample rate is in samples per second. For example, 44100/8000 Data size – The precision the data is stored in.  For example, 8/16 bits Data encoding – What encoding the data type uses. For example, u-law,a-law Channels – How many channels are contained in the audio data.  For example, Stereo 2 channels SoX supports over 20 audio file formats. To get the list of all supported formats, execute sox -h from the command line. One of the major benefits of a command-line audio/mu
Read more

Sox of Silence - Original post - http://digitalcardboard.com/blog/2009/08/25/the-sox-of-silence/

-
Image
The SoX of Silence SoX is, by their own definition,  the Swiss Army knife of audio manipulation. And no doubt it’s full of fun with slicing and dicing and playback and recording and filtering and effects capabilities. But SoX is a command line tool, which means obscure syntax and parameters in order to get things done. I’ve been trying off and on for months to try to understand the  silence  filter from within SoX, which allows one to remove silence from the beginning, middle, or end of the audio. Sounds, simple, doesn’t it?  Well, it should be. Below is the  man page for the  silence  filter : silence  [-l] above-periods [duration threshold[d|%] [below-periods duration threshold[d|%]] Removes silence from the beginning, middle, or end of the audio. Silence is anything below a specified threshold. The above-periods value is used to indicate if audio should be trimmed at the beginning of the audio. A value of zero indicates no silence should be trimmed from the beg
Read more

How to get video or audio duration of a file using ffmpeg?

-
Today we will learn How to get the duration of a file using ffmpeg 1. Format Container Duration - [This works for both Video and Audio Files - better to report numbers using this command] ffprobe -v error -show_entries format=duration \ -of default=noprint_wrappers=1:nokey=1 input.mp4     2. Video Stream Duration - [This works only for Videos]   ffprobe -v error -select_streams v:0 -show_entries stream=duration \ -of default=noprint_wrappers=1:nokey=1 input.mp4     Content author - https://superuser.com/questions/650291/how-to-get-video-duration-in-seconds
Read more