ease bash/sh coding: Has someone right(,), left(,), and len(,) scripts for /usr/bin ?

frenchn00b · 11-06-2008, 01:21 AM

Hi,

Like in basic, right(,), left(,), and len(,) are very very useful.

Has someone right(,), left(,), and len(,) scripts for /usr/bin ?

Thanks
Happy sh tux

would you have the same for :

right.sh

Code:

#!/bin/sh
# echo  $1 is the string
# echo $2 is the number of chars
...?
??
??

left.sh

Code:

#!/bin/sh
# echo  $1 is the string
# echo $2 is the number of chars
...?
??
??

chrism01 · 11-06-2008, 01:32 AM

Not sure if this is what you want, but here are 3 ways to get a string/var length
http://unstableme.blogspot.com/2008/...ngth-bash.html

frenchn00b · 11-16-2008, 08:14 PM

I dont know maybe there is some packages ffor the
/usr/bin ????
already

certainly

those could help a looooooooooooooooot

sundialsvcs · 11-16-2008, 08:30 PM

Why bother?

In Linux, you've probably got (already installed): Perl, PHP, Ruby, Python and more. Any of these full-featured programming languages "go on forever." And you can use any one of them in any command, thanks to "#!command_processor_name" shebang.

So... in my opinion... if you are using "bash scripting" to do anything other than the most-trivial ... "you're missing the point."

jan61 · 11-17-2008, 01:51 PM

Moin,

why search for separate packages? The functions come already shipped with the bash:

Code:

VAR="abcdefg"
echo len=${#VAR}
echo left[3]=${VAR:1:3}
echo right[3]=${VAR:$((${#VAR}-3))}

Jan

frenchn00b · 04-19-2009, 07:30 AM

Quote:

Originally Posted by jan61

Moin,

why search for separate packages? The functions come already shipped with the bash:

Code:

VAR="abcdefg"
echo len=${#VAR}
echo left[3]=${VAR:1:3}
echo right[3]=${VAR:$((${#VAR}-3))}

Jan

would you please have the same for :

right.sh

Code:

#!/bin/sh
# echo  $1 is the string
# echo $2 is the number of chars
...?
??
??

left.sh

Code:

#!/bin/sh
# echo  $1 is the string
# echo $2 is the number of chars
...?
??
??

Hko · 04-19-2009, 01:28 PM

Quote:

Originally Posted by jan61

Code:

VAR="abcdefg"
echo len=${#VAR}
echo left[3]=${VAR:1:3}
echo right[3]=${VAR:$((${#VAR}-3))}

Code:

echo right[3]=${VAR: -3}

jan61 · 04-21-2009, 04:17 PM

Moin,

I still don't understand, why you want to get shell scripts for one liners - you'll create a new subshell every time you call these scripts. The simple use of the shell builtins would prevent you from such resource wasting. But if you really want to do this:

Code:

jan@jack:~/tmp> cat left.sh
VAR=$1
LEN=$2
echo ${VAR:0:$LEN}
jan@jack:~/tmp> cat right.sh
VAR=$1
LEN=$2
echo ${VAR: -$LEN}
jan@jack:~/tmp> ./left.sh WORKS_IN_SHELL 5
WORKS
jan@jack:~/tmp> ./right.sh WORKS_IN_SHELL 5
SHELL

thx to Hko for the hint to the shorter right command. As you see, there was a little bug in the left command (starting at 1, not at 0).

Jan

EDIT: A better way instead of writing shell scripts would be to define aliases or functions in your login scripts or system wide login scripts, for example:

Code:

jan@jack:~/tmp> cat myfunctions
function left() {
  local VAR=$1
  local LEN=$2
  echo ${VAR:0:$LEN}
}

function right() {
  local VAR=$1
  local LEN=$2
  echo ${VAR: -$LEN}
}
jan@jack:~/tmp> . ./myfunctions
jan@jack:~/tmp> left WORKS_IN_SHELL 5
WORKS
jan@jack:~/tmp> right WORKS_IN_SHELL 5
SHELL

Hko · 04-21-2009, 04:31 PM

Quote:

Originally Posted by jan61

I still don't understand, why you want to get shell scripts for one liners - you'll create a new subshell every time you call these scripts. The simple use of the shell builtins would prevent you from such resource wasting.

I was wondering too, but the only thing I could think of was that the OP was asking for a way to do it in sh (i.e. not bash). Since those builtins are bash-specific.

Quote:

Originally Posted by jan61

thx to Hko for the hint to the shorter right command.

You're welcome :-)
FYI: The space between ':' and '-' is needed.

jan61 · 04-21-2009, 04:52 PM

Moin,

Quote:

Originally Posted by Hko

I was wondering too, but the only thing I could think of was that the OP was asking for a way to do it in sh (i.e. not bash). Since those builtins are bash-specific.

This would be an explanation - but why didn't he tell us???

Quote:

Originally Posted by Hko

FYI: The space between ':' and '-' is needed.

*g* - Now I know ;-) I remember: I tried the negative number (without the space!) and was really angry, because it didn't work. The first thing I did with your line was to remove the (totally uncool) space and I was astonished again %-/ But I'm able to learn ...

Jan

BTW: Some weeks ago I noticed, that some old fashioned Korn shells (for example in Sun - ehm, Oracle - Solaris10) now include a subset of bash features. One could look, if the mentioned features are part of the new ksh's.

frenchn00b · 04-21-2009, 10:25 PM

Quote:

Originally Posted by jan61

Moin,

I still don't understand, why you want to get shell scripts for one liners - you'll create a new subshell every time you call these scripts. The simple use of the shell builtins would prevent you from such resource wasting. But if you really want to do this:

Code:

jan@jack:~/tmp> cat left.sh
VAR=$1
LEN=$2
echo ${VAR:0:$LEN}
jan@jack:~/tmp> cat right.sh
VAR=$1
LEN=$2
echo ${VAR: -$LEN}
jan@jack:~/tmp> ./left.sh WORKS_IN_SHELL 5
WORKS
jan@jack:~/tmp> ./right.sh WORKS_IN_SHELL 5
SHELL

thx to Hko for the hint to the shorter right command. As you see, there was a little bug in the left command (starting at 1, not at 0).

Jan

EDIT: A better way instead of writing shell scripts would be to define aliases or functions in your login scripts or system wide login scripts, for example:

Code:

jan@jack:~/tmp> cat myfunctions
function left() {
  local VAR=$1
  local LEN=$2
  echo ${VAR:0:$LEN}
}

function right() {
  local VAR=$1
  local LEN=$2
  echo ${VAR: -$LEN}
}
jan@jack:~/tmp> . ./myfunctions
jan@jack:~/tmp> left WORKS_IN_SHELL 5
WORKS
jan@jack:~/tmp> right WORKS_IN_SHELL 5
SHELL

Thank you !! I was floooding of learning those day, and I put that program on the side.

Thank you !!

frenchn00b · 04-22-2009, 11:03 AM

Quote:

Originally Posted by jan61

Moin,

I still don't understand, why you want to get shell scripts for one liners - you'll create a new subshell every time you call these scripts. The simple use of the shell builtins would prevent you from such resource wasting. But if you really want to do this:

Code:

jan@jack:~/tmp> cat left.sh
VAR=$1
LEN=$2
echo ${VAR:0:$LEN}
jan@jack:~/tmp> cat right.sh
VAR=$1
LEN=$2
echo ${VAR: -$LEN}
jan@jack:~/tmp> ./left.sh WORKS_IN_SHELL 5
WORKS
jan@jack:~/tmp> ./right.sh WORKS_IN_SHELL 5
SHELL

thx to Hko for the hint to the shorter right command. As you see, there was a little bug in the left command (starting at 1, not at 0).

Jan

EDIT: A better way instead of writing shell scripts would be to define aliases or functions in your login scripts or system wide login scripts, for example:

Code:

jan@jack:~/tmp> cat myfunctions
function left() {
  local VAR=$1
  local LEN=$2
  echo ${VAR:0:$LEN}
}

function right() {
  local VAR=$1
  local LEN=$2
  echo ${VAR: -$LEN}
}
jan@jack:~/tmp> . ./myfunctions
jan@jack:~/tmp> left WORKS_IN_SHELL 5
WORKS
jan@jack:~/tmp> right WORKS_IN_SHELL 5
SHELL

working

Code:

#!/usr/bin/bash

function left() {
  local VAR="$1"
  local LEN="$2"
  echo ${VAR:0:$LEN}
}

function right() {
  local VAR="$1"
  local LEN="$2"
  echo ${VAR: -$LEN}
}

function trim() {
  eval $1=` echo $1 |    sed 's/^[[:space:]]*\(.*\)[[:space:]]*$/\1/'   `
}

TEST="  sta   rtKLJK LJKLJKLJKLend "
right "$TEST" 6
left "$TEST" 6
echo $TEST

Code:

$ sh test
KLend
sta
sta rtKLJK LJKLJKLJKLend

jan61 · 04-23-2009, 02:33 PM

Moin,

Quote:

Originally Posted by frenchn00b

Code:

...
function trim() {
  eval $1=` echo $1 |    sed 's/^[[:space:]]*\(.*\)[[:space:]]*$/\1/'   `
}

This does not work on the right side:

Code:

jan@jack:~> VAR="  123  456    "
jan@jack:~> VAR1=`echo "$VAR" | sed 's/^[[:space:]]*\(.*\)[[:space:]]*$/\1/'`
jan@jack:~> echo "[$VAR] [$VAR1]"
[  123  456    ] [123  456    ]

Why? regex are greedy - the second pattern ".*" matches up to the end of line, because the third pattern "[[:space:]]*" can be 0 characters long.

Better use this:

Code:

jan@jack:~> VAR1=`echo "$VAR" | sed 's/^[[:space:]]*//;s/[[:space:]]*$//'`
jan@jack:~> echo "[$VAR] [$VAR1]"
[  123  456    ] [123  456]

If your variables can contain spaces, you should quote them always - otherwise you see an output as in your script - trailing and leading spaces are gone away and spaces in the middle are shortened to one.

Jan