bash ref

## REMOVE FIRST CHARACTER FROM STRING
sed '/^.//'

== Example ==
$ echo "foo" | sed 's/^.//'
oo

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## REMOVE FIRST CHARACTER FROM COLUMN N
awk '{print substr($n,2)}'

== Example ==
$ echo "foo bar" | awk '{print substr($2,2)}'
ar

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## REMOVE PATTERN AND PRECEDING CHARACTERS
sed 's/^.*pattern//'

== Example ==
$ echo "foo,bar" | sed 's/^.*,//'
bar

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## REMOVE ALL LEADING WHITESPACE
sed 's/^[ \t]*//'

== Example ==
$ echo "     foo" | sed 's/^[ \t]*//'
foo

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## REMOVE LAST CHARACTER FROM STRING 
sed 's/.$//'

== Example ==
$ echo "foo" | sed 's/.$//'
fo

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## REMOVE LAST CHARACTER FROM COLUMN N
awk '{print substr($n,1,length($n)-1)}'

== Example ==
$ echo "foo bar" | awk '{print substr($2,1,length($2)-1)}'
ba

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## REMOVE PATTERN AND SUBSEQUENT CHARACTERS
sed 's/pattern.*//'

== Example ==
$ echo "foo,bar" | sed 's/,.*//'
foo

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## USING AWK IN PLACE OF GREP+AWK
# Method 1: For all rows containing pattern print column n
awk '/pattern/{print $n}'

== Example ==
$ cat example.txt
Hello World
foo bar
foo bar

$ awk '/foo/{print $2}' example.txt
bar
bar

# Method 2: For all rows matching pattern in column x, print column n from first match only
awk '/foo/{print $n;exit}'

== Example ==
$ awk '$1=="foo"{print $2;exit}' example.txt
bar

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## PASSING A SHELL VARIABLE TO AWK
# Method 1: Using var to match pattern
awk -v var="$var" '$0~var{print $n}'

== Example ==
$ var=foo \
$ echo "foo bar" | awk -v var="$var" '$0~var{print $2}'
bar

# Method 2: Using var in a condition
awk -v var="$var" '{$n<=>var{print $x}'

 == Example ==
$ cat numbers.txt:
1 2
3 4
5 6
7 8
9 0

$ var=5; awk -v var="$var" '$1>=var{print $2}' numbers.txt
6
8
0

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## PRINT AWK OUTPUT ON SAME LINE
awk '{printf "%s ",$n}'

== Example ==
$ cat list.txt
1
2
3
4

$ awk '$1>=2{printf "%s ",$1}' list.txt
2 3 4

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## MATCH STRING EXACTLY, INCLUDING TOTAL CHARACTERS
grep "\<pattern\>"

== Example ==
$ cat test.txt
foo
foob
fooba
foobar

$ grep "foo" test.txt
foo
foob
fooba
foobar
$ grep "\<foo\>" test.txt
foo