In bash I would like to extract part of many filenames and save that output to another file.
The files are formatted as coffee_{SOME NUMBERS I WANT}.freqdist.
#!/bin/sh
for f in $(find . -name 'coffee*.freqdist)
That code will find all the coffee_{SOME NUMBERS I WANT}.freqdist file. Now, how do I make an array containing just {SOME NUMBERS I WANT} and write that to file?
I know that to write to file one would end the line with the following.
> log.txt
I'm missing the middle part though of how to filter the list of filenames.
You can do it natively in bash as follows:
filename=coffee_1234.freqdist
tmp=${filename#*_}
num=${tmp%.*}
echo "$num"
This is a pure bash solution. No external commands (like sed) are involved, so this is faster.
Append these numbers to a file using:
echo "$num" >> file
(You will need to delete/clear the file before you start your loop.)
If the intention is just to write the numbers to a file, you do not need find command:
ls coffee*.freqdist
coffee112.freqdist coffee12.freqdist coffee234.freqdist
The below should do it which can then be re-directed to a file:
$ ls coffee*.freqdist | sed 's/coffee\(.*\)\.freqdist/\1/'
112
12
234
Guru.
The previous answers have indicated some necessary techniques. This answer organizes the pipeline in a simple way that might apply to other jobs as well. (If your sed doesn't support ‘;’ as a separator, replace ‘;’ with ‘|sed’.)
$ ls */c*; ls c*
fee/coffee_2343.freqdist
coffee_18z8.x.freqdist coffee_512.freqdist coffee_707.freqdist
$ find . -name 'coffee*.freqdist' | sed 's/.*coffee_//; s/[.].*//' > outfile
$ cat outfile
512
18z8
2343
707
