Removing all spaces, tabs, newlines, etc from a variable?

Question

This is the error I am getting and it's failing because of a variable whose value is supposed to be 2 (I am getting this using a select * from tabel). I am getting spaces in that variable.

+ 0 != 
         2
./setjobs[19]: 0:  not found.

How do I remove all those spaces or a newline from that variable? Can tr, sed, or anything help?

This what I am doing:

set_jobs_count=$(echo  "set heading off;
      select count(*) from oppar_db
      where ( oppar_db_job_name, oppar_db_job_rec ) in ($var) ;" | \
  sqlplus -s ${OP_ORA_USER}/${OP_ORA_PASS}@$OPERATIONAL_DB_NAME)

---

This works as suggested:

| sed 's/[[:space:]]//g'

But I still obtain a value like :

  set_jobs_count=
  2

Answer 1

The reason sed 's/[[:space:]]//g' leaves a newline in the output is because the data is presented to sed a line at a time. The substitution can therefore not replace newlines in the data (they are simply not part of the data that sed sees).

Instead, you may use tr

tr -d '[:space:]'

which will remove space characters, form feeds, new-lines, carriage returns, horizontal tabs, and vertical tabs.

Answer 2

In ksh, bash or zsh:

set_jobs_count=…
set_jobs_count=${set_jobs_count//[[:space:]]/}

In any Bourne-like shell, you can remove leading and trailing whitespace and normalize all intermediate whitespace to a single space like this:

set -f
set -- $set_jobs_count
set_jobs_count="$*"
set +f

set -f turns off globbing; if you know that the data contains none of the characters \[?*, you can omit it.

That assumes $IFS contains its default value of space, tab, newline. Other whitespace characters (CR, VT, FF...) are left alone.

Answer 3

As already suggested, use "tr -d '[:space:]'", BUT if that doesn't work, possibly on an older Unix system, one needs to cover all these characters:

\011 HT    '\t' (horizontal tab)
\012 LF    '\n' (new line)
\013 VT    '\v' (vertical tab)
\014 FF    '\f' (form feed)
\015 CR    '\r' (carriage ret)
\040 SPACE ' '  (space)

with this:

tr -d '\011\012\013\014\015\040'

However, perhaps there are other non-visible characters garbling the output, The result from 'select count(*) ...' should be only an integer, so to leave only digits:

tr -dc '0-9'

However, that won't work if there are other characters after the first digits, and then more digits. So, to only return the first digit sequence found:

perl -ane '/\d+/ && print($&) && exit'

## example: will return '11', but raw output looks like '22 33'
(echo -e '\a11\b\b22 33') | perl -ane '/\d+/ && print($&) && exit'

Answer 4

There is a simpler way - use (any) shell word splitting.

Let's create a script like that:

#!/bin/bash
readonly CONN="${RDS_ADMIN}@//${RDS_HOST}/${RDS_DBNAME}"

SCN=$(sqlplus -S $CONN << EOF
SET HEADING OFF
SELECT CURRENT_SCN FROM V\$DATABASE;
EOF
)

echo ">>>$SCN<<<"
SCN=$(echo $SCN)
echo ">>>$SCN<<<"

Here is the output of the script:

oracle@ctrl-dev|265$ ./t.sh
>>>
   87401840<<<
>>>87401840<<<
oracle@ctrl-dev|266$ 

There is no external command required, the downside is VAR=$(echo $VAR) construction which does not look nice.