Skip to main content
Unix & Linux

Return to Question

Mod Moved Comments To Chat
edits to address Q's fm comments
Source Link
Seamus
Seamus
  • 3.9k
  • 2
  • 21
  • 50

Edits for answers to some of the Questions raised in the comments:

EDIT #1:

$ command -V vol-get vol-get is a function vol-get () { amixer sget Master | awk -F"[][]" '/Left:/ { print $2 }' } $ awk --version awk: not an option: --version $ man awk # reveals that I am actually calling `mawk`, Version 1.3.4

EDIT #2:

RE: non-printing characters; note this is a partial c&p from the output (i.e. verbatim):

$ cat -vet ~/.bashrc ... function vol-get() {$ amixer sget Master | awk -F'[][]' '/Left:/ { print $2 }'$ }$ ...

EDIT:

$ command -V vol-get vol-get is a function vol-get () { amixer sget Master | awk -F"[][]" '/Left:/ { print $2 }' } $ awk --version awk: not an option: --version $ man awk # reveals that I am actually calling `mawk`, Version 1.3.4

Edits for answers to some of the Questions raised in the comments:

EDIT #1:

$ command -V vol-get vol-get is a function vol-get () { amixer sget Master | awk -F"[][]" '/Left:/ { print $2 }' } $ awk --version awk: not an option: --version $ man awk # reveals that I am actually calling `mawk`, Version 1.3.4

EDIT #2:

RE: non-printing characters; note this is a partial c&p from the output (i.e. verbatim):

$ cat -vet ~/.bashrc ... function vol-get() {$ amixer sget Master | awk -F'[][]' '/Left:/ { print $2 }'$ }$ ...
address Q in cmt
Source Link
Seamus
Seamus
  • 3.9k
  • 2
  • 21
  • 50

EDIT:

$ command -V vol-get vol-get is a function vol-get () { amixer sget Master | awk -F"[][]" '/Left:/ { print $2 }' } $ awk --version awk: not an option: --version $ man awk # reveals that I am actually calling `mawk`, Version 1.3.4

EDIT:

$ command -V vol-get vol-get is a function vol-get () { amixer sget Master | awk -F"[][]" '/Left:/ { print $2 }' } $ awk --version awk: not an option: --version $ man awk # reveals that I am actually calling `mawk`, Version 1.3.4
Source Link
Seamus
Seamus
  • 3.9k
  • 2
  • 21
  • 50

Why does a 'pipe-to-awk' behave differently inside a function?

I'm using alsa to fiddle around with the volume on a Bluetooth speaker I have connected. It's a 1-speaker setup; just something to provide some background.

I can 'get' the volume setting fm the CLI as follows:

$ amixer sget Master Simple mixer control 'Master',0 Capabilities: pvolume pswitch pswitch-joined Playback channels: Front Left - Front Right Limits: Playback 0 - 65536 Mono: Front Left: Playback 22938 [35%] [on] Front Right: Playback 22938 [35%] [on]

I can 'set' the volume fm the CLI as follows:

$ amixer sset Master 50% Simple mixer control 'Master',0 Capabilities: pvolume pswitch pswitch-joined Playback channels: Front Left - Front Right Limits: Playback 0 - 65536 Mono: Front Left: Playback 32768 [50%] [on] Front Right: Playback 32768 [50%] [on]

I don't need all this verbosity, so I decided to create a function, and two aliases in my ~/.bashrc file to reduce that. The function is not working as I expected:

From the CLI, this works fine:

$ amixer sget Master | awk -F"[][]" '/Right:/ { print $2 }' 35%

But when I put this into my function statement in ~/.bashrc, it works differently:

# functions & aliases for alsa mixer/volume control function vol-get() { amixer sget Master | awk -F"[][]" '/Left:/ { print $2 }' } export -f vol-get alias vol-up='amixer sset Master 5%+ > /dev/null && vol-get' alias vol-dn='amixer sset Master 5%- > /dev/null && vol-get'

Re-reading ~/.bashrc & running the vol-get function yields the following:

$ . ~/.bashrc $ vol-get Front Left: Playback 22938 [35%] [on] # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ?? what happened here ?? $ vol-up Front Left: Playback 26215 [40%] [on] $

So - I'm close, but I don't understand why my | awk ... behaves differently inside the function than it does on the command line. Can someone explain and correct this?