Is there a function to return the length of a string?
The fastest way, not requiring external programs (but not usable in Bourne shells):
# POSIX
${#varname}or for Bourne shells:
# Bourne expr "$varname" : '.*'
(expr prints the number of characters matching the pattern .*, which is the length of the string.)
or:
# Bourne, with GNU expr(1) expr length "$varname"
(BSD/GNU expr only)
This second version is not specified in POSIX, so is not portable across all platforms. However, if $varname expands to "length", the first version will fail with BSD/GNU expr.
A portable way is:
expr \( "X$varname" : ".*" \) - 1
One may also use awk:
# Bourne
awk -v x="$varname" 'BEGIN {print length(x)}'Though that one will fail for values of $varname that contain backslash characters, so you may prefer:
# Bourne with POSIX awk
awk 'BEGIN {print length(ARGV[1]);exit}' "$varname"
Similar needs:
# Korn/Bash
${#arrayname[@]}Returns the number of elements in an array.
# Korn/Bash
${#arrayname[i]}Returns the length of the array's element i.