Length of String in Bash

To get the length of a string stored in a variable, say:

myvar="some string"
size=${#myvar} 

To confirm it was properly saved, echo it:

$ echo "$size"
11

I wanted the simplest case, finally this is a result:

echo -n 'Tell me the length of this sentence.' | wc -m;
36

You can use:

MYSTRING="abc123"
MYLENGTH=$(printf "%s" "$MYSTRING" | wc -c)

• wc -c or wc --bytes for byte counts = Unicode characters are counted with 2, 3 or more bytes.
• wc -m or wc --chars for character counts = Unicode characters are counted single until they use more bytes.

In response to the post starting:

If you want to use this with command line or function arguments...

with the code:

size=${#1}

There might be the case where you just want to check for a zero length argument and have no need to store a variable. I believe you can use this sort of syntax:

if [ -z "$1" ]; then
    #zero length argument 
else
    #non-zero length
fi

See GNU and wooledge for a more complete list of Bash conditional expressions.

If you want to use this with command line or function arguments, make sure you use size=${#1} instead of size=${#$1}. The second one may be more instinctual but is incorrect syntax.

Using your example provided

#KISS (Keep it simple stupid)
size=${#myvar}
echo $size

Here is couple of ways to calculate length of variable :

echo ${#VAR}
echo -n $VAR | wc -m
echo -n $VAR | wc -c
printf $VAR | wc -m
expr length $VAR
expr $VAR : '.*'

and to set the result in another variable just assign above command with back quote into another variable as following:

otherVar=`echo -n $VAR | wc -m`   
echo $otherVar

I know that the Q and A's are old enough, but today I faced this task for first time. Usually I used the ${#var} combination, but it fails with unicode: most text I process with the bash is in Cyrillic... Based on @atesin's answer, I made short (and ready to be more shortened) function which may be usable for scripting. That was a task which led me to this question: to show some message of variable length in pseudo-graphics box. So, here it is:

$ cat draw_border.sh
#!/bin/sh
#based on 
border()
{
local BPAR="$1"
local BPLEN=`echo $BPAR|wc -m`
local OUTLINE=\|\ "$1"\ \|
# line below based on 
# comment of Bit Twiddler Jun 5, 2021 @ 8:47
local OUTBORDER=\+`head -c $(($BPLEN+1))</dev/zero|tr '\0' '-'`\+
echo $OUTBORDER
echo $OUTLINE
echo $OUTBORDER
}
border "Généralités"
border 'А вот еще одна '$LESSCLOSE' '
border "pure ENGLISH"

And what this sample produces:

$ draw_border.sh
+-------------+
| Généralités |
+-------------+
+----------------------------------+
| А вот еще одна /usr/bin/lesspipe |
+----------------------------------+
+--------------+
| pure ENGLISH |
+--------------+

First example (in French?) was taken from someone's example above. Second one combines Cyrillic and the value of some variable. Third one is self-explaining: only 1s 1/2 of ASCII chars.

I used echo $BPAR|wc -m instead of printf ... in order to not rely on if the printf is buillt-in or not.

Above I saw talks about trailing newline and -n parameter for echo. I did not used it, thus I add only one to the $BPLEN. Should I use -n, I must add 2.

To explain the difference between wc -m and wc -c, see the same script with only one minor change: -m was replaced with -c

$ draw_border.sh
+----------------+
| Généralités |
+----------------+
+---------------------------------------------+
| А вот еще одна /usr/bin/lesspipe |
+---------------------------------------------+
+--------------+
| pure ENGLISH |
+--------------+

Accented characters in Latin, and most of characters in Cyrillic are two-byte, thus the length of drawn horizontals are greater than the real length of the message. Hope, it will save some one some time :-)

p.s. Russian text says "here is one more"

p.p.s. Working "two-liner"

#!/bin/sh
#based on 
border()
{
# line below based on 
# comment of Bit Twiddler Jun 5, 2021 @ 8:47
local OUTBORDER=\+`head -c $(( $(echo "$1"|wc -m) +1))</dev/zero|tr '\0' '-'`\+
echo $OUTBORDER"\n"\|\ "$1"\ \|"\n"$OUTBORDER
}
border "Généralités"
border 'А вот еще одна '$LESSCLOSE' '
border "pure ENGLISH"

In order to not clutter the code with repetitive OUTBORDER's drawing, I put the forming of OUTBORDER into separate command

Maybe just use:

echo $myvar | wc -c