Fun with grep for newbies
by teckk from LinuxQuestions.org on (#4VJV3)
Fun with grep for newer members.
Lets start with this list of items to use.
Code:list="
[12.1]
cat
horse
MOUSE
Cow
[12.3]
house
[49.1]
[49.2]
chair
[55.1]
dog
car
26
28
132
aardvark
"grep examples:
Code:#just the numeric items between []
grep -oP '(?<=\[).*(?=\])' <<< "$list"
12.1
12.3
49.1
49.2
55.1
grep -oP '\[\K[^]]+' <<< "$list"
12.1
12.3
49.1
49.2
55.1
#keep the brackets
grep -o '\[.*\]' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
grep '[0-9][0-9].[0-9]' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
#items that have 3 digits
grep '[0-9][0-9][0-9]' <<< "$list"
132
grep '[0-9]\{3\}' <<< "$list"
132
#one or more digits
grep '[0-9]\{1,\}' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
26
28
132
#start with digit
grep '^[0-9]' <<< "$list"
26
28
132
#do not start with digit
grep '[^0-9]' <<< "$list"
[12.1]
cat
horse
MOUSE
Cow
[12.3]
house
[49.1]
[49.2]
chair
[55.1]
dog
car
aardvark
#only alpha
grep '[[:alpha:]]' <<< "$list"
cat
horse
MOUSE
Cow
house
chair
dog
car
aardvark
#start with c
grep '^c' <<< "$list"
cat
chair
car
#end with e
grep 'e$' <<< "$list"
horse
house
#first char of each item in list
grep -oP "^\K." <<< "$list"
[
c
h
M
[
h
[
[
c
[
d
c
2
2
1
a
#starts with upper case
grep "^[[:upper:]]" <<< "$list"
MOUSE
Cow
grep '^[A-Z]' <<< "$list"
MOUSE
Cow
#2 items after match
grep -A 2 '\[12.1\]' <<< "$list"
[12.1]
cat
horse
#does not contain a-z
grep -v '[A-Za-z]' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
26
28
132
#does not contain digit
grep -v '[0-9]' <<< "$list"
cat
horse
MOUSE
Cow
house
chair
dog
car
aardvark
#count matches
grep -c '[0-9]' <<< "$list"
8
#items that are 3 char long
grep '^...$' <<< "$list"
cat
Cow
dog
car
132
#multiple patterns
grep '^c\|h' <<< "$list"
cat
horse
house
chair
car
#search for blank lines(there are 2, top and bottom of $list)
grep '^$' <<< "$list"That's a start.
Anyone else is welcome to post more examples in this grep/egrep thread if you want.
See: man grep
Lets start with this list of items to use.
Code:list="
[12.1]
cat
horse
MOUSE
Cow
[12.3]
house
[49.1]
[49.2]
chair
[55.1]
dog
car
26
28
132
aardvark
"grep examples:
Code:#just the numeric items between []
grep -oP '(?<=\[).*(?=\])' <<< "$list"
12.1
12.3
49.1
49.2
55.1
grep -oP '\[\K[^]]+' <<< "$list"
12.1
12.3
49.1
49.2
55.1
#keep the brackets
grep -o '\[.*\]' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
grep '[0-9][0-9].[0-9]' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
#items that have 3 digits
grep '[0-9][0-9][0-9]' <<< "$list"
132
grep '[0-9]\{3\}' <<< "$list"
132
#one or more digits
grep '[0-9]\{1,\}' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
26
28
132
#start with digit
grep '^[0-9]' <<< "$list"
26
28
132
#do not start with digit
grep '[^0-9]' <<< "$list"
[12.1]
cat
horse
MOUSE
Cow
[12.3]
house
[49.1]
[49.2]
chair
[55.1]
dog
car
aardvark
#only alpha
grep '[[:alpha:]]' <<< "$list"
cat
horse
MOUSE
Cow
house
chair
dog
car
aardvark
#start with c
grep '^c' <<< "$list"
cat
chair
car
#end with e
grep 'e$' <<< "$list"
horse
house
#first char of each item in list
grep -oP "^\K." <<< "$list"
[
c
h
M
[
h
[
[
c
[
d
c
2
2
1
a
#starts with upper case
grep "^[[:upper:]]" <<< "$list"
MOUSE
Cow
grep '^[A-Z]' <<< "$list"
MOUSE
Cow
#2 items after match
grep -A 2 '\[12.1\]' <<< "$list"
[12.1]
cat
horse
#does not contain a-z
grep -v '[A-Za-z]' <<< "$list"
[12.1]
[12.3]
[49.1]
[49.2]
[55.1]
26
28
132
#does not contain digit
grep -v '[0-9]' <<< "$list"
cat
horse
MOUSE
Cow
house
chair
dog
car
aardvark
#count matches
grep -c '[0-9]' <<< "$list"
8
#items that are 3 char long
grep '^...$' <<< "$list"
cat
Cow
dog
car
132
#multiple patterns
grep '^c\|h' <<< "$list"
cat
horse
house
chair
car
#search for blank lines(there are 2, top and bottom of $list)
grep '^$' <<< "$list"That's a start.
Anyone else is welcome to post more examples in this grep/egrep thread if you want.
See: man grep