Bash command not found

INFO: this project relies on CocoaPods to install extra packages.
The CocoaPods command about to be sent is "pod install"
[A]ccept or [C]hange? Default is to [A]ccept if no answer in 5 seconds.

Delegating "pod install" job to CocoaPods daemon...
Daemon started.
Preparing staging directory...
Sending command: "pod install"
========================== CocoaPods output BEGIN ===========================
Analyzing dependencies
Adding spec repo `trunk` with CDN `https://cdn.cocoapods.org/`
Downloading dependencies
Installing BoringSSL-GRPC (0.0.24)
[!] /usr/local/bin/bash -c
set -e
set -e
# Add a module map and an umbrella header
mkdir -p src/include/openssl
cat > src/include/openssl/umbrella.h <<EOF
  #include "ssl.h"
  #include "crypto.h"
  #include "aes.h"
  /* The following macros are defined by base.h. The latter is the first file included by the
     other headers. */
  #if defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64)
  #  include "arm_arch.h"
  #endif
  #include "asn1.h"
  #include "asn1_mac.h"
  #include "asn1t.h"
  #include "blowfish.h"
  #include "cast.h"
  #include "chacha.h"
  #include "cmac.h"
  #include "conf.h"
  #include "cpu.h"
  #include "curve25519.h"
  #include "des.h"
  #include "dtls1.h"
  #include "hkdf.h"
  #include "md4.h"
  #include "md5.h"
  #include "obj_mac.h"
  #include "objects.h"
  #include "opensslv.h"
  #include "ossl_typ.h"
  #include "pkcs12.h"
  #include "pkcs7.h"
  #include "pkcs8.h"
  #include "poly1305.h"
  #include "rand.h"
  #include "rc4.h"
  #include "ripemd.h"
  #include "safestack.h"
  #include "srtp.h"
  #include "x509.h"
  #include "x509v3.h"
EOF
cat > src/include/openssl/BoringSSL.modulemap <<EOF
  framework module openssl {
    umbrella header "umbrella.h"
    textual header "arm_arch.h"
    export *
    module * { export * }
  }
EOF

# To avoid symbol conflict with OpenSSL, gRPC needs to rename all the BoringSSL symbols with a
# prefix. This is done with BoringSSL's BORINGSSL_PREFIX mechanism
# (https://github.com/google/boringssl/blob/75148d7abf12bdd1797fec3c5da9a21963703516/BUILDING.md#building-with-prefixed-symbols).
# The required prefix header file boringssl_prefix_symbols.h is not part of BoringSSL repo at
# this moment. It has to be generated by BoringSSL's users and be injected to BoringSSL build.
# gRPC generates this file in script /tools/distrib/upgrade_boringssl_objc.sh. This script
# outputs a gzip+base64 encoded version of boringssl_prefix_symbols.h because of Cocoapods'
# limit on the 'prepare_command' field length. The encoded header is generated from
# /src/boringssl/boringssl_prefix_symbols.h. Here we decode the content and inject the header to
# the correct location in BoringSSL.
case "$(uname)" in
  Darwin) opts="" ;;
       *) opts="--ignore-garbage" ;;
esac
base64 --decode $opts <<EOF | gunzip > src/include/openssl/boringssl_prefix_symbols.h
  H4sICAAAAAAC/2JvcmluZ3NzbF9wcmVmaXhfc3ltYm9scy5oAKydXXPbuJZo3+dXuO683Kk6NRM7nW73
  fVNsJdG0Y/tIck9nXliURNk8oUiFoOy4f/0FQErEx94g94arTs10LK21KQDEF0Hgv/7r7DErszptss3Z
  6vX0j2RV1Xn5KESR7Otsm/9MnrJ0k9X/KZ7OqvLso/50sbg5W1e7Xd78v7PV7xfvL7a/Zxe/ZR9+/fVy
  ............... REMOVED THIS PART ..................
  F4GRE54Uu4hrB1y32Bxc/yjkZsan3//697F/SrEfPxquMLZ/Dnm1fcFBS0qL8t3fwvXzkdnhvW7Lbn9E
  yuENfCln05Zvn9AToQIe+JvWL8zRz11am2I5baIgKKOf3O4u/VXIYnaKMl5fqL8GdRfYO6HU60eGkjIt
  G+RHKOAi4/Dr4YrbmwsonaORd3hyxlw6U9kSGL4S8MjvyoQX7GLQyHuo6w/rbqE/TFq4+2l/lw7qGUNU
  ynDzD1yyKfaf3/4P5m1j6i2mBAA=
EOF

# We are renaming openssl to openssl_grpc so that there is no conflict with openssl if it exists
find . -type f \( -path '*.h' -or -path '*.cc' -or -path '*.c' \) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include <openssl/;#include <openssl_grpc/;g'

# Include of boringssl_prefix_symbols.h does not follow Xcode import style. We add the package
# name here so that Xcode knows where to find it.
find . -type f \( -path '*.h' -or -path '*.cc' -or -path '*.c' \) -print0 | xargs -0 -L1 sed -E -i'.grpc_back' 's;#include <boringssl_prefix_symbols.h>;#include <openssl_grpc/boringssl_prefix_symbols.h>;g'

/usr/local/bin/bash: line 68: base64: command not found
gunzip: (stdin): unexpected end of file
=========================== CocoaPods output END ============================
NOTICE: this command returned a non-success exit status (1).
Press any key to continue . . .