Download File From Linux Server To Mac

Download A File In Linux
Download File From Linux Server To Mac Download

Name

Securely downloading files with scp is aimed primarily at advanced users who are using ssh and the command line regularly in either macOS X, bsd, or linux. For those with adequate command line experience, using ssh and scp to download remote files is easy and, conveniently, after the file transfer has completed, the remote connection will end. I have a file which is an executable sitting on the server. When I just use scp to copy it down to my desktop which is a mac i get bash -./fig up cannot execute binary file. I believe this is because it came from linux, and now I am trying to run it on a mac terminal.

sx, sb, sz - XMODEM, YMODEM, ZMODEM file send

Synopsis

sz [-+8abdefkLlNnopqTtuvyY] file ...
sb [-adfkqtuv] file ...
sx [-akqtuv] file
sz [-oqtv] -c COMMAND
sz [-oqtv] -i COMMAND
sz -TT

Description

Sz uses the ZMODEM, YMODEM or XMODEM error correcting protocol to send one or more files over a dial-in serial port to a variety of programs runningunder PC-DOS, CP/M, Unix, VMS, and other operating systems.

While rz is smart enough to be called from cu(1), very few versions of cu(1) are smart enough to allow sz to work properly. Unixflavors of Professional-YAM are available for such dial-out application.

Sz sends one or more files with ZMODEM protocol.

ZMODEM greatly simplifies file transfers compared to XMODEM. In addition to a friendly user interface, ZMODEM provides Personal Computer and other users anefficient, accurate, and robust file transfer method.

ZMODEM provides complete END-TO-END data integrity between application programs. ZMODEM's 32 bit CRC catches errors that sneak into even the mostadvanced networks.

Advanced file management features include AutoDownload (Automatic file Download initiated without user intervention), Display of individual and total filelengths and transmission time estimates, Crash Recovery, selective file transfers, and preservation of exact file date and length.

Output from another program may be piped to sz for transmission by denoting standard input with '-':

ls -l | sz -

The program output is transmitted with the filename sPID.sz where PID is the process ID of the sz program. If the environment variable ONAMEis set, that is used instead. In this case, the Unix command:

ls -l | ONAME=con sz -ay -

will send a 'file' to the PC-DOS console display. The -y option instructs the receiver to open the file for writing unconditionally. The -aoption causes the receiver to convert Unix newlines to PC-DOS carriage returns and linefeeds.

Sb batch sends one or more files with YMODEM or ZMODEM protocol. The initial ZMODEM initialization is not sent. When requested by the receiver,sb supports YMODEM-g with 'cbreak' tty mode, XON/XOFF flow control, and interrupt character set to CAN (^X). YMODEM-g (Professional-YAMg option) increases throughput over error free channels (direct connection, X.PC, etc.) by not acknowledging each transmitted sector.

On Unix systems, additional information about the file is transmitted. If the receiving program uses this information, the transmitted filelength controls the exact number of bytes written to the output dataset, and the modify time and file mode are set accordingly.

Sx sends a single file with XMODEM or XMODEM-1k protocol (sometimes incorrectly called 'ymodem'). The user must supply the filename to both sending and receiving programs.

If sz is invoked with $SHELL set and iff that variable contains the string rsh , rbash or rksh (restricted shell), szoperates in restricted mode. Restricted mode restricts pathnames to the current directory and PUBDIR (usually /usr/spool/uucppublic) and/or subdirectoriesthereof.

The fourth form sends a single COMMAND to a ZMODEM receiver for execution. Sz exits with the COMMAND return value. If COMMAND includes spaces orcharacters special to the shell, it must be quoted.

The fifth form sends a single COMMAND to a ZMODEM receiver for execution. Sz exits as soon as the receiver has correctly received the command, beforeit is executed.

The sixth form (sz -TT) attempts to output all 256 code combinations to the terminal. In you are having difficulty sending files, this command lets you seewhich character codes are being eaten by the operating system.

If sz is invoked with stdout and stderr to different datasets, Verbose is set to 2, causing frame by frame progress reports to stderr. This may bedisabled with the q option.

The meanings of the available options are:

-+, --append

Instruct the receiver to append transmitted data to an existing file (ZMODEM only).

-2, --twostop

use two stop bits (if possible). Do not use this unless you know what you are doing.

-8, --try-8k

Try to go up to 8KB blocksize. This is incompatible with standard zmodem, but a common extension in the bbs world. (ZMODEM only).

--start-8k

Start with 8KB blocksize. Like --try-8k.

-a, --ascii

Convert NL characters in the transmitted file to CR/LF. This is done by the sender for XMODEM and YMODEM, by the receiver for ZMODEM.

-b, --binary

(ZMODEM) Binary override: transfer file without any translation.

-B NUMBER, --bufsize NUMBER

Use a readbuffer of NUMBER bytes. Default ist 16384, which should be enough for most situations. If you have a slow machine or a bad disk interfaceor suffer from other hardware problems you might want to increase the buffersize. -1 or auto use a buffer large enough to buffer the whole file.Be careful with this option - things normally get worse, not better, if the machine starts to swap.

Using this option turns of memory mapping of the input file. This increases memory and cpu usage.

-c COMMAND, --command COMMAND

Send COMMAND to the receiver for execution, return with COMMAND's exit status.

-C N, --command-tries N

Retry to send command N times (default: 11).

-d, --dot-to-slash

Change all instances of '.' to '/' in the transmitted pathname. Thus, C.omenB0000 (which is unacceptable to MSDOS or CP/M) is transmitted as C/omenB0000. Ifthe resultant filename has more than 8 characters in the stem, a '.' is inserted to allow a total of eleven.

This option enables the --full-path option.

--delay-startup N

Wait N seconds before doing anything.

-e, --escape

Escape all control characters; normally XON, XOFF, DLE, CR-@-CR, and Ctrl-X are escaped.

Force the sender to rename the new file if a file with the same

name already exists.

-f, --full-path

Send Full pathname. Normally directory prefixes are stripped from the transmitted filename.

This is also turned on with to --dot-to-slash option.

-h, --help

give help.

-i COMMAND, --immediate-command COMMAND

Send COMMAND to the receiver for execution, return immediately upon the receiving program's successful recption of the command.

-k, --1k

(XMODEM/YMODEM) Send files using 1024 byte blocks rather than the default 128 byte blocks. 1024 byte packets speed file transfers at high bit rates. (ZMODEMstreams the data for the best possible throughput.)

-L N, --packetlen N

Use ZMODEM sub-packets of length N. A larger N (32 <= N <= 1024) gives slightly higher throughput, a smaller N speeds error recovery. The default is128 below 300 baud, 256 above 300 baud, or 1024 above 2400 baud.

-m N, --min-bps N

Stop transmission if BPS-Rate (Bytes Per Second) falls below N for a certain time (see --min-bps-time option).

-M N, --min-bps-time

Used together with --min-bps. Default is 120 (seconds).

-l N, --framelen N

Wait for the receiver to acknowledge correct data every N (32 <= N <= 1024) characters. This may be used to avoid network overrun when XOFFflow control is lacking.

-n, --newer

(ZMODEM) Send each file if destination file does not exist. Overwrite destination file if source file is newer than the destination file.

-N, --newer-or-longer

(ZMODEM) Send each file if destination file does not exist. Overwrite destination file if source file is newer or longer than the destination file.

-o, --16-bit-crc

(ZMODEM) Disable automatic selection of 32 bit CRC.

-O, --disable-timeouts

Disable read timeout handling. This makes lsz hang if the other side doesn't send anything, but increases performance (not much) and decreases system load(reduces number of system calls by about 50 percent).

Use this option with care.

-p, --protect

(ZMODEM) Protect existing destination files by skipping transfer if the destination file exists.

-q, --quiet

Quiet suppresses verbosity.

-R, --restricted

Restricted mode: restricts pathnames to the current directory and PUBDIR (usually /usr/spool/uucppublic) and/or subdirectories thereof.

-r, --resume

(ZMODEM) Resume interrupted file transfer. If the source file is longer than the destination file, the transfer commences at the offset in the source filethat equals the length of the destination file.

-s HH:MM, --stop-at HH:MM

Stop transmission at HH hours, MM minutes. Another variant, using +N instead of HH:MM, stops transmission in Nseconds.

-S, --timesync

Download A File In Linux

enable timesync protocol support. See timesync.doc for further information.

This option is incompatible with standard zmodem. Use it with care.

--syslog[=off]

turn syslogging on or off. the default is set at configure time. This option is ignored if no syslog support is compiled in.

-t TIM, --timeout TIM

Change timeout to TIM tenths of seconds.

-T, --turbo

Do not escape certain characters (^P, ^P|0x80, telenet escape sequence [CR + @]). This improves performance by about 1 percent and shouldn't hurt in thenormal case (but be careful - ^P might be useful if connected through a terminal server).

--tcp

Try to initiate a TCP/IP connection. lsz will ask the receiving zmodem to open a TCP/IP connection. All handshaking (which address / port to use) will bedone by the zmodem programs.

You will normally not want to use this option as lrzsz is the only zmodem which understands what to do (private extension). You might want to use thisoption if the two programs are connected (stdin/out) over a slow or bad (not 8bit clean) network connection.

Use of this option imposes a security risk, somebody else could connect to the port in between. See SECURITY for details.

--tcp-client ADDRESS:PORT

Act as a tcp/ip client: Connect to the given port.

See --tcp-server for more information.

--tcp-server

Act as a server: Open a socket, print out what to do, wait for connection.

You will normally not want to use this option as lrzsz is the only zmodem which understands what to do (private extension). You might want to use this ifyou have to use zmodem (for which reason whatever), and cannot use the --tcp option of lsz (perhaps because your telnet doesn't allow to spawn alocal program with stdin/stdout connected to the remote side).

If you use this option you have to start lsz with the --tcp-client ADDRESS:PORT option. lrz will print the address and port on startup.

Use of this option imposes a security risk, somebody else could connect to the port in between. See SECURITY for details.

-u

Unlink the file after successful transmission.

-U, --unrestrict

Turn off restricted mode (this is not possible if running under a restricted shell).

-w N, --windowsize N

Limit the transmit window size to N bytes (ZMODEM).

-v, --verbose

Verbose output to stderr. More v's generate more output.

-X, --xmodem

use XMODEM protocol.

-y, --overwrite

Instruct a ZMODEM receiving program to overwrite any existing file with the same name.

-Y, --overwrite-or-skip

Instruct a ZMODEM receiving program to overwrite any existing file with the same name, and to skip any source files that do have a file with the samepathname on the destination system.

--ymodem

use ZMODEM protocol.

-Z, --zmodem

use ZMODEM protocol.

Security

Restricted mode restricts pathnames to the current directory and PUBDIR (usually /var/spool/uucppublic) and/or subdirectories thereof, and disables remotecommand execution.

Restricted mode is entered if the R option is given or if lsz detects that it runs under a restricted shell or if the environment variableZMODEM_RESTRICTED is found.

Restricted mode can be turned of with the U option if not running under a restricted shell.

Environment

ZNULLS

may be used to specify the number of nulls to send before a ZDATA frame.

SHELL

lsz recognizes a restricted shell if this variable includes rsh or rksh

ZMODEM_RESTRICTED

lrz enters restricted mode if the variable is set.

TMPDIR

If this environment variable is set its content is used as the directory to place in the answer file to a timesync request. TMP Used insteadof TMPDIR if TMPDIR is not set. If neither TMPDIR nor TMP is set /tmp will be used.

Examples

ZMODEM File Transfer (Unix to DSZ/ZCOMM/Professional-YAM)
% sz -a *.c
This single command transfers all .c files in the current Unix directory with conversion (-a) to end of line conventions appropriate to the receivingenvironment. With ZMODEM AutoDownload enabled, Professional-YAM and ZCOMM will automatically recieve the files after performing a security check.

% sz -Yan *.c *.h
Send only the .c and .h files that exist on both systems, and are newer on the sending system than the corresponding version on the receiving system,converting Unix to DOS text format.
$ sz -Yan file1.c file2.c file3.c foo.h baz.h Â®(for VMS)

ZMODEM Command Download (Unix to Professional-YAM)
cpszall:all sz -c 'c:;cd /yam/dist' sz -ya $(YD)/*.me sz -yqb y*.exe sz -c 'cd /yam' sz -i '!insms'
This Makefile fragment uses sz to issue commands to Professional-YAM to change current disk and directory. Next, sz transfers the .mefiles from the $YD directory, commanding the receiver to overwrite the old files and to convert from Unix end of line conventions to PC-DOS conventions. Thethird line transfers some .exe files. The fourth and fifth lines command Pro-YAM to change directory and execute a PC-DOS batch file insms .Since the batch file takes considerable time, the -i form is used to allow sz to exit immediately.

XMODEM File Transfer (Unix to Crosstalk)
% sx -a foo.c
ESC
rx foo.c
The above three commands transfer a single file from Unix to a PC and Crosstalk with sz translating Unix newlines to DOS CR/LF. This combination is muchslower and far less reliable than ZMODEM.

Error Messages

'Caught signal 99' indicates the program was not properly compiled, refer to 'bibi(99)' in rbsb.c for details.

Vms Version

The VMS version does not support wild cards. Because of VMS DCL, upper case option letters muse be represented by proceding the letter.

The current VMS version does not support XMODEM, XMODEM-1k, or YMODEM.

VMS C Standard I/O and RMS may interact to modify the file contents.

Files

32 bit CRC code courtesy Gary S. Brown.

sz.c, crctab.c, rbsb.c, zm.c, zmodem.h Unix source files

sz.c, crctab.c, vrzsz.c, zm.c, zmodem.h, vmodem.h, vvmodem.c, VMS source files.

/tmp/szlog stores debugging output (sz -vv) (szlog on VMS).

Testing Feature

The command 'sz -T file' exercises the Attn sequence error recovery by commanding errors with unterminated packets. The receiving program shouldcomplain five times about binary data packets being too long. Each time sz is interrupted, it should send a ZDATA header followed by another defectivepacket. If the receiver does not detect five long data packets, the Attn sequence is not interrupting the sender, and the Myattn string insz.c must be modified.

After 5 packets, sz stops the 'transfer' and prints the total number of characters 'sent' (Tcount). The difference between Tcount and 5120 representsthe number of characters stored in various buffers when the Attn sequence is generated.

Bugs

Calling sz from most versions of cu(1) doesn't work because cu's receive process fights sz for characters from the modem.

On at least one BSD system, sz would hang or exit when it got within a few kilobytes of the end of file. Using the '-w 8192' flag fixed the problem. Thereal cause is unknown, perhaps a bug in the kernel TTY output routines.

Programs that do not properly implement the specified file transfer protocol may cause sz to 'hang' the port for a minute or two. This problem iscorrected by using ZCOMM, Pro-YAM, or other program with a correct implementation of the specified protocol.

Many programs claiming to support YMODEM only support XMODEM with 1k blocks, and they often don't get that quite right.

XMODEM transfers add up to 127 garbage bytes per file. XMODEM-1k and YMODEM-1k transfers use 128 byte blocks to avoid extra padding.

YMODEM programs use the file length transmitted at the beginning of the transfer to prune the file to the correct length; this may cause problems withsource files that grow during the course of the transfer. This problem does not pertain to ZMODEM transfers, which preserve the exact file lengthunconditionally.

Most ZMODEM options are merely passed to the receiving program; some do not implement all these options.

Circular buffering and a ZMODEM sliding window should be used when input is from pipes instead of acknowledging frames each 1024 bytes. If no files can beopened, sz sends a ZMODEM command to echo a suitable complaint; perhaps it should check for the presence of at least one accessible file before gettinghot and bothered. The test mode leaves a zero length file on the receiving system.

A few high speed modems have a firmware bug that drops characters when the direction of high speed transmissson is reversed. The environment variable ZNULLSmay be used to specify the number of nulls to send before a ZDATA frame. Values of 101 for a 4.77 mHz PC and 124 for an AT are typical.

Referenced By

picocom(8),ztelnet(1)

Someday you may need to get the SSL certificate of a website and save it locally.

For example, you could get an error saying that you can’t clone a Git repository due to a self-signed certificate and to resolve this issue you would need to download the SSL certificate and make it trusted by your Git client.

In the following article i am showing how to export the SSL certificate from a server (site URL) using Google Chrome, Mozilla Firefox and Internet Explorer browsers as well as how to get SSL certificate from the command line, using openssl command.

Cool Tip: Create a self-signed SSL Certificate! Read more →

Export SSL Certificate

Google Chrome

Export the SSL certificate of a website using Google Chrome:

Click the Secure button (a padlock) in an address bar
Click the Show certificate button
Go to the Details tab
Click the Export button
Specify the name of the file you want to save the SSL certificate to, keep the “Base64-encoded ASCII, single certificate” format and click the Save button

Mozilla Firefox

Export the SSL certificate of a website using Mozilla Firefox: