Techbits #11: Avoiding "Useless use of" commands in Unix

Let's check out another interesting Unix-related Techbit related to avoiding the usage of commands when they're not necessary.

Such usages are also fondly referred in "Useless use of ..." category awards :-) There're many varieties under this class like "Useless use of cat", "Useless use of grep & awk", "Useless use of wc -l" etc. Provided below are few.

Useless use of "cat"

cat file.txt | grep pattern can very well be expressed as grep pattern file.txt

Useless use of "grep"

ps -ef | grep java | grep -v grep can be ps -ef | grep '[j]ava'

ps -ef | grep java | awk '{print $2}' can just become ps -ef | awk '/java/ {print $2}'

Useless use of "wc"

ls -1 | grep pattern | wc -l can be written as ls -1 | grep -c pattern