Bash Tricks II: Repetitive tasks on files

[ Thanks to Edmundo
for this link. ]

“Second we have the while read variable; do x; y; z;
done. This construct allows us to read from the standard output
line by line placing the content of each line in a variable
(multiple variables can be used, in that case a single word from
the standard input will be placed in each variable). In our case,
we used $filename as our variable (be careful not to use $ on the
while read).

“Then the “s. These kids allow us to run a command so that its
output can be assigned. In our case, we are listing the files of a
tgz file, grepping to find the pattern of the file we are looking
for and then counting the lines that come out of grep. The number
of lines is what is saved in the variable $lines.”

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