Bash Script to get the first characters of a string

onesikgypo · 11-13-2008, 11:51 PM

Hey,

I'm looking for a way to "filter" everything but the first characters of a piece of string. For example in:

Joe.Smith.Annual.Financial.Statement.Reviews

it would filter to "jsafsr" (this must be lowercase). I'm currently unsure of the most efficient way to do this, so would really appreciate any help that could be given.

Thankyou.

Stéphane Ascoët · 11-14-2008, 02:10 AM

I would use "cut" to store each part in a separate variable and then obtain the first letter of each one.

angel115 · 11-14-2008, 02:45 AM

Hi Onesikgypo,

As alternative to cut you can use the following as well:

Code:

echo "Joe.Smith.Annual.Financial.Statement.Reviews" | sed -e 's/[a-z]*//g' | sed -e 's/\.//g' | tr [:upper:] [:lower:]

sed -e 's/[a-z]*//g'
Will remove all lower case characters

sed -e 's/\.//g'
Will remove the dots

tr [:upper:] [:lower:]
Will convert the string left to lowercase.

colucix · 11-14-2008, 02:53 AM

Using awk:

Code:

string=Joe.Smith.Annual.Financial.Statement.Reviews
echo $string | awk -F. '
{ for ( i=1; i<=NF; i++ )
    printf "%s", tolower(substr($i,1,1))
}'

colucix · 11-14-2008, 02:58 AM

Using the shell:

Code:

#!/bin/bash
string="Joe.Smith.Annual.Financial.Statement.Reviews"
string=${string//./ }
for i in $(echo $string)
do
  printf "%s" ${i:0:1}
done | tr [:upper:] [:lower:]

onesikgypo · 11-14-2008, 03:07 AM

Hey all,

Thankyou for the responses thus far, i like the shell script one that colucix has posted, simply because it is shell, and it doesnt have the pre-requirement that all the letters were starting with a capital letter, wich is good incase one time the string was Financial.report.For.jones.Smith or alike.

I do have a question re that script however, the first is that for some reason it seems to automatically add a proceeding echo line to the output, to make myself more clear:

stringtest3=${stringtest3//./ }
for i in $(echo $stringtest3)
do
printf "%s" ${i:0:1}
done | tr [:upper:] [:lower:]

date2add=$(date +%y.%m.%d)
echo "$date2add"

and following from the example above, it is currently echoing

jsafsr08.11.14

Now though this was going to be my ultimate goal (i was just going to add it on) it seems a bit weird that it would add itself on in its current format.

Also, i was wondering how i could put the output of that section of the script that was posted into a variable, rather then just echoing it?

Thankyou.

colucix · 11-14-2008, 04:12 AM

I don't understand where the newline is added. Please, use code tags to embed the code, so that newlines, blank spaces and tabs are preserved when posting. For the second part of your question, to store the result in a variable simply concatenate each character with the previous value of the variable itself, for example:

Code:

#!/bin/bash
stringtest3=Joe.Smith.Annual.Financial.Statement.Reviews
stringtest3=${stringtest3//./ }
for i in $(echo $stringtest3)
do
  newstring=$newstring$(echo ${i:0:1} | tr [:upper:] [:lower:])
done
echo $newstring

Suppose you have this code in test.sh:

Code:

$ ./test.sh
jsafsr

The same if you want to add the date:

Code:

newstring=$newstring$(date +%y.%m.%d)

onesikgypo · 11-14-2008, 04:18 AM

Ok Thankyou,

I didnt actually change anything in your art of the code so it stays the same at:

Code:

stringtest3=${stringtest3//./ }
for i in $(echo $stringtest3)
do
printf "%s" ${i:0:1}
done | tr [:upper:] [:lower:]

I just had some more code below that piece, which was

Code:

date2add=$(date +%y.%m.%d)
echo "$date2add"

So the code as a whole simply looked like

Code:

stringtest3=${stringtest3//./ }
for i in $(echo $stringtest3)
do
printf "%s" ${i:0:1}
done | tr [:upper:] [:lower:]


date2add=$(date +%y.%m.%d)
echo "$date2add"

Now With That Coding, what im guessing i shoul dhave seen when i ran the script was:

Code:

jsafsr
08.11.14

But what actually outputted was:

Code:

jsafsr08.11.14

Which seems a bit odd to me?

Not sure if you undrstand the issue i was talking about now?

Thankyou for the help in placing it in a variable.

radoulov · 11-14-2008, 04:22 AM

A solution for the initial requirement with zsh:

Code:

printf "%.1s" ${(Ls:.:)s=Joe.Smith.Annual.Financial.Statement.Reviews}

colucix · 11-14-2008, 04:28 AM

Quote:

Originally Posted by onesikgypo

Not sure if you undrstand the issue i was talking about now?

Yes, of course. Very clear now. The printf statement in my script just formats the output as "%s", that is a string. If you want a newline character, you have to explicitly put it in the format specification, as for "%s\n". But this would not give the desired result, since every character would be followed by a newline and the result would have been

Code:

j
s
a
f
s
r
08.11.14

To put a newline, just use a simple echo statement without arguments.

colucix · 11-14-2008, 04:32 AM

Quote:

Originally Posted by radoulov

A solution for the initial requirement with zsh:

Code:

printf "%.1s" ${(Ls:.:)s=Joe.Smith.Annual.Financial.Statement.Reviews}

Very nice! radoulov, you're an ace one-liner, as always!

jan61 · 11-14-2008, 09:52 AM

Moin,

a shorter sed example:

Code:

echo "Joe.Smith.Annual.Financial.Statement.Reviews" | \
sed -r 's/([A-Za-z])[^.]*\.?/\1/g' | tr '[:upper:]' '[:lower:]'

It works case insensitive.

Jan

radoulov · 11-14-2008, 09:57 AM

Well,
this is a Linux forum so I'm assuming GNU sed is available:

Code:

sed -r 's/(.)[^.]*\.?/\L\1/g'