Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
wc −w gives only the word count.
wc −l gives only the line count.
wc −c gives only the character count.
wc −L gives only the length of the longest line.
Using wc to count how many .txt files are in current working directory:
$ ls *.txt | wc −l
# Will work as long as none of the "*.txt" files have a linefeed in their name.
# Alternative ways of doing this are:
# find . −maxdepth 1 −name \*.txt −print0 | grep −cz .
# (shopt −s nullglob; set −− *.txt; echo $#)
# Thanks, S.C.
Using wc to total up the size of all the files whose names begin with letters in the range d − h
bash$ wc [d−h]* | grep total | awk '{print $3}'
71832
Using wc to count the instances of the word "Linux" in the main source file for this book.
bash$ grep Linux abs−book.sgml | wc −l
50
See also Example 12−30 and Example 16−7.
Certain commands include some of the functionality of wc as options.
... | grep foo | wc −l
# This frequently used construct can be more concisely rendered.
... | grep −c foo
# Just use the "−c" (or "−−count") option of grep.
tr
# Thanks, S.C.
character translation filter.
Must use quoting and/or brackets, as appropriate. Quotes prevent the shell from
reinterpreting the special characters in tr command sequences. Brackets should be
quoted to prevent expansion by the shell.
Either tr "A−Z" "*"