expr

[root@web02-7 scripts]# cat expr.sh 
#!/bin/bash
if expr "$1" : ".*\.pub" &>/dev/null
then
echo "you are using $1"
else
echo "please use *.pub file"
fi
[root@web02-7 scripts]# sh -x expr.sh
+ expr '' : '.*\.pub'
+ echo 'please use *.pub file'
please use *.pub file
[root@web02-7 scripts]# sh -x expr.sh k.bak  #不是执行pub文件
+ expr k.bak : '.*\.pub'
+ echo 'please use *.pub file'
please use *.pub file
[root@web02-7 scripts]# sh -x expr.sh k.pub
+ expr k.pub : '.*\.pub'
+ echo 'you are using k.pub'
you are using k.pub

　　

[root@web02-7 scripts]# which ssh-copy-id
/usr/bin/ssh-copy-id

[root@web02-7 scripts]# which ssh-copy-id
/usr/bin/ssh-copy-id
[root@web02-7 scripts]# cat `which ssh-copy-id`
#!/bin/sh

# Shell script to install your public key on a remote machine
# Takes the remote machine name as an argument.
# Obviously, the remote machine must accept password authentication,
# or one of the other keys in your ssh-agent, for this to work.

ID_FILE="${HOME}/.ssh/id_rsa.pub"

if [ "-i" = "$1" ]; then
  shift
  # check if we have 2 parameters left, if so the first is the new ID file
  if [ -n "$2" ]; then
    if expr "$1" : ".*\.pub" > /dev/null ; then
      ID_FILE="$1"
    else
      ID_FILE="$1.pub"
    fi
    shift         # and this should leave $1 as the target name
  fi
else
  if [ x$SSH_AUTH_SOCK != x ] ; then
    GET_ID="$GET_ID ssh-add -L"
  fi
fi

if [ -z "`eval $GET_ID`" ] && [ -r "${ID_FILE}" ] ; then
  GET_ID="cat ${ID_FILE}"
fi

if [ -z "`eval $GET_ID`" ]; then
  echo "$0: ERROR: No identities found" >&2
  exit 1
fi

if [ "$#" -lt 1 ] || [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
  echo "Usage: $0 [-i [identity_file]] [user@]machine" >&2
  exit 1
fi

{ eval "$GET_ID" ; } | ssh $1 "exec sh -c 'umask 077; test -d ~/.ssh || mkdir ~/.ssh ; cat >> ~/.ssh/authorized_keys && (test -x /sbin/restorecon && /sbin/restorecon ~/.ssh ~/.ssh/authorized_keys >/dev/null 2>&1 || true)'" || exit 1

cat <<EOF
Now try logging into the machine, with "ssh '$1'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

EOF