I know you’re not asking for awk protips but you can prefix the block with a match condition for processing.
... | grep foo | awk ‘{print $6}’ | ...
becomes
... | awk ‘/foo/{print $6}’ | ...
If you start working this into your awk habits you’ll find delightful little edge cases that you can handle with other expressions before the block (you can, for example, match specific fields).
Yikes. The syntax I had was wrong anyway. Should have been
awk 'BEGIN {FS=":"};{print $1}'
One benefit of the FS variable over -F, at least in original awk, is that by using FS the delimiter can be more than one character. I guess that's why I remember FS before I remember -F. More flexible.
That is not how FS is set; It's set with -F. And there is actually no need to use -v, passing variables at the end works consistently across all AWK's and always has:
To pile on :-) you often want -w (match word) flag to grep.
In awk, I couldn't find how to do this. I tried /\bfoo\b/ and /\<foo\>/ but neither worked. I don't know why and don't care enough which brings me to my major awk irritation ...
It doesn't use extended or perl REs, which makes it quite different to ruby, perl, python, java. Now, according to the man page it does; at least on OSX (man re_format) but as mentioned it didn't work for me.
GNU awk supports \< and \> for start and end of word anchors, which works for GNU grep/sed as well
GNU awk also supports \y which is same as \b as well as \B for opposite (same as GNU grep/sed)
Intererstingly, there's a difference between the three types of word anchors:
$ # \b matches both start and end of word boundaries
$ # 1st and 3rd line have space as second character
$ echo 'I have 12, he has 2!' | grep -o '\b..\b'
I
12
,
he
2
$ # \< and \> strictly match only start and end word boundaries respectively
$ echo 'I have 12, he has 2!' | grep -o '\<..\>'
12
he
$ # -w ensures there are no word characters around the matching text
$ # same as: grep -oP '(?<!\w)..(?!\w)'
$ echo 'I have 12, he has 2!' | grep -ow '..'
12
he
2!
On the other hand, grep can be far faster for searching alone than awk. I almost always use an initial grep for the string that will most reduce the input to the rest of the pipeline. Later, it feels idiomatic to mix in awk with matches like you suggested
... | grep foo | awk ‘{print $6}’ | ...
becomes
... | awk ‘/foo/{print $6}’ | ...
If you start working this into your awk habits you’ll find delightful little edge cases that you can handle with other expressions before the block (you can, for example, match specific fields).