On 23/07/2020 16:37, Jerry Geis wrote:
Thanks, when I change it do the following I get a syntax error
#!/bin/bash
#
while read LINE
do
echo $LINE
done < cat list.txt
You don't use "cat" here; it's not needed at all. You write:
done < list.txt
This tells the shell to redirect the stdin of the while loop from the
file "list.txt".
People in the unix world have made a mess of code everywhere by
superfluously using "cat". In the old usenet days, anyone who posted
shell code with unnecessary use of cat used to be awarded a prize (and
it was not something to be proud of, but to be embarrassed about).
"cat" is short for "concatenate", and for that purpose, it is perfect.
When you want to take two or more sources of data, and combine them,
then cat is the perfect tool, eg:
cat file1 file2 file3 > combined-file
But for most other tasks, if you're using "cat", then you're almost
certainly misusing it. For example, people who do:
cat file | grep something
This makes the shell fork and run cat, and then the shell has to setup a
pipe to pass the data to grep. Too much overhead. They don't know that
they can just do:
grep something file
and let the grep command read the file itself.
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