RegexRecipes

From Genunix

Contents 1 perl 1.1 Turn every n lines into one line 1.2 Search for text between the lines that contain MB00251 and MB00598 1.3 Print line -n of filename 2 vi 2.1 Remove ^M 2.2 Add hashes in front of every line 3 ed 3.1 Deletes the first line containing "regular" 3.2 globally deletes all lines containing "regular" 3.3 Replaces the first occurrence of "regular" with "complex" on current line 3.4 Globally replaces all occurrences of "regular" with "complex" on current line 3.5 Globally replaces all occurrences of "regular" with "complex" 4 sed 4.1 Globally replaces all occurrences of "regular" with "complex" 4.2 Outputs those lines that contain "regular" 4.3 Links 5 awk 5.1 Print the first field of everyline in file "filename" 6 grep 6.1 Print all lines that either do not begin with the "#"(hash) character or aren't blank lines 7 regex 7.1 Replace IP address "176.161.12.131" with "176.161.12.134"

perl

Turn every n lines into one line

---

• perl -ne 'if($.%n !=0) {chomp;} print $_;' filename

Search for text between the lines that contain MB00251 and MB00598

---

• perl -ne 'print if /MB00251/ .. /MB00598/'

Print line -n of filename

---

• perl -ne 'if($.==n){print;exit}' filename

vi

Remove ^M

•  :1,$ s/^v^m//g

Add hashes in front of every line

•  :1,$ s/\(.*\)/#\1/

ed

Deletes the first line containing "regular"

• /regular/d

globally deletes all lines containing "regular"

• g/regular/d

Replaces the first occurrence of "regular" with "complex" on current line

• s/regular/complex/

Globally replaces all occurrences of "regular" with "complex" on current line

• s/regular/complex/g

Globally replaces all occurrences of "regular" with "complex"

• g/regular/s/regular/complex/g

sed

Globally replaces all occurrences of "regular" with "complex"

• s/regular/complex/
  • ie: sed 's/regular/complex/' filename

Outputs those lines that contain "regular"

• sed -n -e 's/regular/complex/' filename

Links

• http://www.cs.hmc.edu/tech_docs/qref/sed.html

awk

Print the first field of everyline in file "filename"

• awk '{ print $1 }' filename

===Match all lines that contain regular expression "regular"

• awk -F, '/regular/ { print $1 }' list
  • ("-F", change field separators to a comma)

grep

Print all lines that either do not begin with the "#"(hash) character or aren't blank lines

(Useful when you wish to view a config file without the comments)

• egrep -v "^#|^$"

regex

Replace IP address "176.161.12.131" with "176.161.12.134"

• 1,$ s/176\.161\.12\.131;/168\.161\.12\.131;176\.161\.12\.134;/g