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Tag: shell

Shell script using FFMPEG convert to mp4 results in new video with .mp4 extension attached twice

I am converting an entire folder of videos to MP4. The script works except that the new videos have “.mp4” attached twice to them. For example. ‘video.mp3’ would be ‘video.mp3.mp4’ after conversion. Below is the shell script. TIA Answer This will strip the last file extension: ${file%.*} So you’d want ${file%.*}.mp4 Here is a good reference for string manipulation in

Partially replace string using ‘sed’ shell command

I need to delete the <#> in the following pattern: Outputs should be like: I was trying to do this sed ‘s/(vdd1[a-z]*).<[0-9]>/1/’ file1 > file2 But it gives me “vdd1” all the way. How can I do it correctly? Answer The dot . after the paren is matching the letter after the 1. You need to get rid of it.

Is space considered a metacharacter in Bash?

I have searched for the list of metacharacters in Bash but space is not enlisted. I wonder if I’m right by assuming that space is the “token separation character” in Bash, since it not only works as such with Shell programs or builtins but also when creating an array through compound assignment – quotes escape spaces, just like they do

bash order-of-operations in math context: Wrong value assigned

Given the linux shell code, Why does $b equal 2? I split the code into three steps: $b equals 1 this time, why? P.S. Neither a nor b is initialized. Answer Because you set b = a, then bash waits for last assigning of a. In b will be assigned same value as the value assigned to a. EDIT 1)

While loop to test if files with a given pattern exist in bash

I want to check with a file loop like this, if files with a given pattern exist: If more files like 12aaa-Stock.txt, 34aaa-Stock.txt are present I have a message error like binary operator expected. Answer You can work around this by using a for-loop, e.g,. As long as there are no files found, the for-loop has one item to process

How to run eval spawn ssh and expect in background?

I created a script to get in inside an Access Point (AP) using ssh and execute some commands and I used expect to interact with shell. The scripts works fine when it is running on foreground, but when I try to execute the same script in background using & to fork the process, it stop at spawn ssh command at

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