下面是我的嵌入式系统busybox ash shell版本，我最初采用了Orwellophile的变体:

urlencode()
{
    local S="${1}"
    local encoded=""
    local ch
    local o
    for i in $(seq 0 $((${#S} - 1)) )
    do
        ch=${S:$i:1}
        case "${ch}" in
            [-_.~a-zA-Z0-9]) 
                o="${ch}"
                ;;
            *) 
                o=$(printf '%%%02x' "'$ch")                
                ;;
        esac
        encoded="${encoded}${o}"
    done
    echo ${encoded}
}

urldecode() 
{
    # urldecode <string>
    local url_encoded="${1//+/ }"
    printf '%b' "${url_encoded//%/\\x}"
}

对于那些正在寻找不需要perl的解决方案的人来说，这里有一个只需要hexdump和awk的解决方案:

url_encode() {
 [ $# -lt 1 ] && { return; }

 encodedurl="$1";

 # make sure hexdump exists, if not, just give back the url
 [ ! -x "/usr/bin/hexdump" ] && { return; }

 encodedurl=`
   echo $encodedurl | hexdump -v -e '1/1 "%02x\t"' -e '1/1 "%_c\n"' |
   LANG=C awk '
     $1 == "20"                    { printf("%s",   "+"); next } # space becomes plus
     $1 ~  /0[adAD]/               {                      next } # strip newlines
     $2 ~  /^[a-zA-Z0-9.*()\/-]$/  { printf("%s",   $2);  next } # pass through what we can
                                   { printf("%%%s", $1)        } # take hex value of everything else
   '`
}

通过网络上的几个地方和当地的一些试验和错误拼接在一起。效果很好!

另一个选择是使用jq:

$ printf %s 'input text'|jq -sRr @uri
input%20text
$ jq -rn --arg x 'input text' '$x|@uri'
input%20text

-r(——raw-output)输出字符串的原始内容，而不是JSON字符串字面量。-n(——null-input)不从STDIN读取输入。

-R(——raw-input)将输入行视为字符串，而不是将其解析为JSON，而-sR(——slurp——raw-input)将输入读入单个字符串。如果你的输入只包含一行，或者你不想用%0A替换换行符，你可以用-Rr替换-sRr:

$ printf %s\\n multiple\ lines of\ text|jq -Rr @uri
multiple%20lines
of%20text
$ printf %s\\n multiple\ lines of\ text|jq -sRr @uri
multiple%20lines%0Aof%20text%0A

或者这个百分比编码所有字节:

xxd -p|tr -d \\n|sed 's/../%&/g'

Uni2ascii非常方便:

$ echo -ne '你好世界' | uni2ascii -aJ
%E4%BD%A0%E5%A5%BD%E4%B8%96%E7%95%8C

我发现在python中可读性更好:

encoded_value=$(python3 -c "import urllib.parse; print urllib.parse.quote('''$value''')")

三重'确保单引号的值不会有伤害。Urllib在标准库中。它的工作，例如这个疯狂的(现实世界)url:

"http://www.rai.it/dl/audio/" "1264165523944Ho servito il re d'Inghilterra - Puntata 7

awk版本的直接链接:http://www.shelldorado.com/scripts/cmds/urlencode 我用了很多年了，效果很好

:
##########################################################################
# Title      :  urlencode - encode URL data
# Author     :  Heiner Steven (heiner.steven@odn.de)
# Date       :  2000-03-15
# Requires   :  awk
# Categories :  File Conversion, WWW, CGI
# SCCS-Id.   :  @(#) urlencode  1.4 06/10/29
##########################################################################
# Description
#   Encode data according to
#       RFC 1738: "Uniform Resource Locators (URL)" and
#       RFC 1866: "Hypertext Markup Language - 2.0" (HTML)
#
#   This encoding is used i.e. for the MIME type
#   "application/x-www-form-urlencoded"
#
# Notes
#    o  The default behaviour is not to encode the line endings. This
#   may not be what was intended, because the result will be
#   multiple lines of output (which cannot be used in an URL or a
#   HTTP "POST" request). If the desired output should be one
#   line, use the "-l" option.
#
#    o  The "-l" option assumes, that the end-of-line is denoted by
#   the character LF (ASCII 10). This is not true for Windows or
#   Mac systems, where the end of a line is denoted by the two
#   characters CR LF (ASCII 13 10).
#   We use this for symmetry; data processed in the following way:
#       cat | urlencode -l | urldecode -l
#   should (and will) result in the original data
#
#    o  Large lines (or binary files) will break many AWK
#       implementations. If you get the message
#       awk: record `...' too long
#        record number xxx
#   consider using GNU AWK (gawk).
#
#    o  urlencode will always terminate it's output with an EOL
#       character
#
# Thanks to Stefan Brozinski for pointing out a bug related to non-standard
# locales.
#
# See also
#   urldecode
##########################################################################

PN=`basename "$0"`          # Program name
VER='1.4'

: ${AWK=awk}

Usage () {
    echo >&2 "$PN - encode URL data, $VER
usage: $PN [-l] [file ...]
    -l:  encode line endings (result will be one line of output)

The default is to encode each input line on its own."
    exit 1
}

Msg () {
    for MsgLine
    do echo "$PN: $MsgLine" >&2
    done
}

Fatal () { Msg "$@"; exit 1; }

set -- `getopt hl "$@" 2>/dev/null` || Usage
[ $# -lt 1 ] && Usage           # "getopt" detected an error

EncodeEOL=no
while [ $# -gt 0 ]
do
    case "$1" in
        -l) EncodeEOL=yes;;
    --) shift; break;;
    -h) Usage;;
    -*) Usage;;
    *)  break;;         # First file name
    esac
    shift
done

LANG=C  export LANG
$AWK '
    BEGIN {
    # We assume an awk implementation that is just plain dumb.
    # We will convert an character to its ASCII value with the
    # table ord[], and produce two-digit hexadecimal output
    # without the printf("%02X") feature.

    EOL = "%0A"     # "end of line" string (encoded)
    split ("1 2 3 4 5 6 7 8 9 A B C D E F", hextab, " ")
    hextab [0] = 0
    for ( i=1; i<=255; ++i ) ord [ sprintf ("%c", i) "" ] = i + 0
    if ("'"$EncodeEOL"'" == "yes") EncodeEOL = 1; else EncodeEOL = 0
    }
    {
    encoded = ""
    for ( i=1; i<=length ($0); ++i ) {
        c = substr ($0, i, 1)
        if ( c ~ /[a-zA-Z0-9.-]/ ) {
        encoded = encoded c     # safe character
        } else if ( c == " " ) {
        encoded = encoded "+"   # special handling
        } else {
        # unsafe character, encode it as a two-digit hex-number
        lo = ord [c] % 16
        hi = int (ord [c] / 16);
        encoded = encoded "%" hextab [hi] hextab [lo]
        }
    }
    if ( EncodeEOL ) {
        printf ("%s", encoded EOL)
    } else {
        print encoded
    }
    }
    END {
        #if ( EncodeEOL ) print ""
    }
' "$@"