check if one string comes before another

Shell Programming and Scripting
1

I want to search a file to check if there is string a before string b:
string a, b might not necessarily be in the file, and to return a boolean

string a

(any text)

string b

i have tried for an hour to do this with perl, grep, etc. but no luck
grep doesnt search for patterns over multiple lines it seems?

I want something like
boolean result = string1 (any text) string 2 (input file name)

any text can be over multiple lines (its a php file)

2

Try this...

result=$( awk '/string1/{f=1}/string2/ && f{print "true"}' input_file )

--ahamed

3

Another way:

result=$( awk '/string2/ && f{print "true";exit}/string1/{f++}' input_file )
4

thanks
im not sure about the first one, it doesnt work when the pattern occurs more than once

ill try the second one

---------- Post updated at 07:25 AM ---------- Previous update was at 07:23 AM ----------

what does the {f++} mean?

---------- Post updated at 07:29 AM ---------- Previous update was at 07:25 AM ----------

does the exit mean that it exits the program? its part of a program so it should be running still

---------- Post updated at 07:31 AM ---------- Previous update was at 07:29 AM ----------

its not working
it doesnt detect it as true when the pattern exists

5

Paste a proper input file with possible combinations and which pattern are you referring to...

--ahamed

6

when there are multiple results, $result becomes:

true
true
true
true
true
true
true
true

but i need it to say just "true"

if [ "$result" == "true" ]

string1
text
string2
string2
string2

matches string1 coming before string2
but its giving:
true
true
true

but i need it to give a single "true"

---------- Post updated at 08:03 AM ---------- Previous update was at 07:49 AM ----------

i put in

if [[ "$result" == *"true"* ]]

for now if there are multiple matches does that work?

7

Try this...

result=$( awk '/string1/{f=1}/string2/&&f{p=1}END{if(p==1)print "true"}' input_file )

--ahamed

---------- Post updated at 05:14 AM ---------- Previous update was at 05:09 AM ----------

Updated the code with search pattern!

--ahamed

---------- Post updated at 05:16 AM ---------- Previous update was at 05:14 AM ----------

This does meet your requirement!
exit here will only exit the awk command after printing the result.

Which is your OS? If Solaris, use nawk!

--ahamed

8

You need only one pattern match to set the value to true, after that you can exit.

Check your input and patterns again.