Ubuntu Manpage: rlwrap - readline wrapper

Provided by: rlwrap_0.46.1-1build2_amd64

NAME

       rlwrap - readline wrapper

SYNOPSIS

       rlwrap [rlwrap-options] command ...

DESCRIPTION

       rlwrap  runs  the specified command, intercepting user input in order to provide readline's line editing,
       persistent history and completion.

       rlwrap tries (and almost succeeds) to be completely transparent - you (or your  shell)  shouldn't  notice
       any  difference  between command and rlwrap command - except the added readline functionality, of course.
       This should even hold true when you are re-directing, piping and sending signals from and to command, and
       when command manipulates its terminal settings, working directory or (with the -U option) command line.

       There are many options to add (programmable) completion, handle multi-line  input,  colour  and  re-write
       prompts. If you don't need them (and you probably don't), you can skip the rest of this manpage, although
       some of those options could make your command line quite a bit more comfortable...

OPTIONS

-a[password_prompt], --always-readline[=password_prompt]
Always remain in "readline mode" (see below), regardless of command's terminal settings. If
rlwrap "does nothing" this is the option to use, as command is apparently already doing its own
line editing. NB: With this option, rlwrap will echo (and save) passwords, unless you give
command's password prompt as an argument.

The argument is optional; if given, it has to directly follow a short option without an
intervening space (-aPassword:) and a long option with an equals sign
(--always-readline=Password:).

The -N (--no-children) option can be used to avoid wrapping pagers and editors called from
command; this should make them much more usable

-A[!], --ansi-colour-aware[=!]
Prompts that use colour, or use other CSI codes to e.g. set window titles or enable bracketed-
paste will confuse rlwrap, especially at the end of long input lines. This option will usually
(but by no means always) make rlwrap better behaved in such cases.

Giving '!' as an argument will make rlwrap remove all color codes from the prompt.

The argument is optional; if given, it has to directly follow a short option without an
intervening space (-A!) and a long option with an equals sign (--ansi-colour-aware=!).

-b, --break-chars list_of_characters
Consider the specified characters word-breaking (whitespace is always word-breaking). This
determines what is considered a "word", both when completing and when building a completion word
list from files specified by -f options following (not preceding!) it. Default list
(){}[],'+-=&^%$#@";|\ Unless -c is specified, / and . (period) are included in the default list.

-c, --complete-filenames
Complete filenames (filename completion is always case-sensitive, even with the -i option). On
Linux, OS X, FreeBSD and Solaris rlwrap will keep track of command's working directory, so that
relative filenames will be completed as one would expect.

-C, --command-name command_name|N
Use command_name instead of command to determine the names of history and completion files, and to
initialise readline (as specified in ~/.inputrc). A numeric argument N > 0 means: use the Nth
argument counting backwards from the end of the argument list

-D, --history-no-dupes n
How aggressively to weed out duplicate entries from the input history. If n = 0, all inputs are
kept in the history list, if n = 1 (this is the default) consecutive duplicates are dropped from
the list, while n = 2 will make rlwrap drop all previous occurrences (in the current session) of
the current input from the list.

-e, --extra-char-after-completion char
By default, rlwrap appends a space after any inserted completion text. Use this option to change
this to '' (don't insert anything) or some other character.

-E, --always-echo
By default, rlwrap avoids displaying passwords by echoing '***' whenever the client clears the
ECHO flag on its input. This option will make rlwrap ignore this ECHO flag and always echo the
user's input. (-aPassword: will still work as expected)

-f, --file file
Split file into words (using the default word-breaking characters, or those specified by
--break-chars), and add them to the completion word list. This option can be given more than once,
and adds to the default completion list in $RLWRAP_HOME or /usr/share/rlwrap/completions.

Specifying -f . will make rlwrap use the current history file as a completion word list.

-g, --forget-matching regexp
Forget (i.e. never put into the history list) input lines that match the POSIX 1003.2 regular
expression regexp. The match is always case-insensitive. perl-style character classes like '\d'
are not recognised, use '[:digit:]'. For more about regular expressions, see regex (7)

-h, --help
Print a short help message.

-H, --history-filename file
Read command history from file (and write it back there if --histsize >= 0)

-i, --case-insensitive
Ignore case when completing (filename completion remains case-sensitive). This option has to come
before any -f options.

-I, --pass-sigint-as-sigterm
Send a TERM signal to command when an INT is received (e.g. when you press CTRL-C).

-l, --logfile file
When in readline mode, append command's output (including echo'ed user input) to file (creating
file when it doesn't exist).

-m[newline_substitute], --multi-line[=newline_substitute]
Enable multi-line input using a "newline substitute" character sequence (" \ ",
[space-backslash-space] by default). Newline substitutes are translated to newlines before sending
the input to command. With this option, you can call an external editor $RLWRAP_EDITOR on the
(expanded) current input with the rlwrap_call_editor key (CTRL-^ by default) The argument is
optional; if given, it has to directly follow a short option without an intervening space (-m';;')
and a long option with an equals sign (--multi-line=';;').

-M, --multi-line-ext .ext
Call multi-line-editor on temporary files with filename extension .ext (useful for e.g. automatic
syntax colouring)

-n, --no-warnings
Don't print warnings.

-N, --no-children
When rlwrap is invoked with the --always-readline option, editors and pagers that are called by
the client will be pretty unusable, as they will see your keypresses only if you press ENTER.
rlwrap -N will avoid this problem by switching to direct mode if it thinks command is waiting for
one of its children.

-o, --one-shot
Send an EOF to command after accepting the first line of input

-O, --only-cook regexp
Only ever "cook" prompts that match regexp, which can be preceded by '!', meaning that all
matching candidate prompts will be cooked immediately ("confident mode").

-p[colour], --prompt-colour[=colour]
Use one of the colour names black, red, green, yellow, blue, cyan, purple (=magenta) or white, or
an ANSI-conformant <colour_spec> to colour any prompt displayed by command. An uppercase colour
name (Yellow or YELLOW ) gives a bold prompt. Prompts that already contain (colour) escape
sequences or one of the readline "ignore markers" (ASCII 0x01 and 0x02) are not coloured. This
option implies --ansi-colour-aware. You can also use a colour spec of the form
<attr>;<fg>[;<bg>], for example -p'1;31' will give a bold red prompt on the current background
(this is the default when no argument is given). Google for 'ANSI color' to learn more about
colour codes. The argument is optional; if given, it has to directly follow a short option
without an intervening space (-p'Red') and a long option with an equals sign
(--prompt-colour='Red').

-P, --pre-given text
Start rlwrap with text in its edit buffer (this will automatically set the --always-readline
option).

-q, --quote-characters list_of_characters
Assume that the given characters act as quotes, e.g. when matching parentheses. Take care to
escape the list properly for your shell (example: -q "\"'", which happens to be the default, or -q
"\"" which will be better for lisp-like input)

-r, --remember
Put all words seen on in- and output on the completion list.

-R, --renice
Make rlwrap nicer than command (cf nice (1)). This may prevent rlwrap from interrupting command to
display a prompt when command is still "thinking" about what to output next.

-s, --histsize N
Limit the history list to N entries, truncating the history file (default: 300). A negative size
-N (even -0) means the same as N, but treats the history file as read-only.

-S, --substitute-prompt prompt
Substitute the specified prompt for command's own prompt. Mainly useful when command doesn't have
a prompt.

-t, --set-term-name name
Set command's TERM to name. Programs that confuse rlwrap with fancy screen control codes can
sometimes be tamed by specifying -t dumb

-U, --mirror-arguments
(linux only) Keep track of command's arguments as seen by the ps (1) command, and mirror them in
rlwrap's own arguments This can be useful for commands that overwrite command-line password
arguments that would be exposed by rlwrap without this option. The mirroring takes place after the
first user input, or every few milliseconds, if you use the --polling option.

-v, --version
Print rlwrap version.

-w, --wait-before-prompt timeout
In order to determine if command's last output is a prompt, rlwrap waits timeout milliseconds
after receiving it. Only when no more output has arrived, it is cooked (coloured, filtered and/or
replaced by a substitute prompt) and displayed as a prompt. Before this the prompt is displayed
"uncooked". Most users won't notice, but heavy cookers can prepend the timeout with a minus sign,
making rlwrap hold back the prompt until it has been cooked ("patient mode"). This will prevent
flashing of the prompt, but it will also interfere with long output lines and make switches from
direct to readline mode less reliable. Default timeout: 40 ms

-W, --polling
EXPERIMENTAL: Wake up every timeout millisecs, where timeout is the same as for the -w
(--wait-before-prompt) option, 40 ms by default. This is used to sense the slave's interrupt
character and ISIG flag and to adjust stdin's terminal settings accordingly, even before you press
a key. Try this option e.g. when CTRL-C acts differently on command with, and without, rlwrap.

-z, --filter some_filter
Use some_filter to change rlwrap's behaviour. Filters can be used to keep certain input out of the
history, to change the prompt, to implement simple macros, programmable hotkeys for e.g. fuzzy
history search, and programmable completion. rlwrap comes with a perl and a python module to make
filter writing easy. (cf. RlwrapFilter(3pm) for the perl module, the python one is very similar) A
number of example filters are installed in the directory /usr/share/rlwrap/filters.

rlwrap -z listing

lists all currently installed filters, while

rlwrap -z some_filter

displays information about some_filter

If some_filter needs arguments, you should quote the whole filter command line:

rlwrap -z 'some_filter args' command ...
rlwrap -z 'pipeline filter1 ... : filter2 ... : ...' command ...

If this command line contains shell metacharacters, rlwrap passes it to the system shell for
parsing.

As filters have to follow a special protocol, shell commands like sed and grep cannot be used as
rwlrap filters. They can, however, be converted into filters by the makefilter filter:

rlwrap -z 'makefilter egrep -i --color "error|$"' command

will color all occurrences of "error" (or "Error") in command's output, while

rlwrap -z 'makefilter --message-type history sed -e s"/whisky/lemonade/"' command

sanitises your drinking history. Both filters can be combined using the pipeline filter, of
course.

EXAMPLES

       Run nc (netcat) with command-line editing and history
          rlwrap nc

       Wrap smbclient (which uses readline itself), keep passwords out of the history and don't interfere with
       pagers (like less) called by smbclient.
          rlwrap -aPassword: -N smbclient //PEANUT/C

       Wrap sensitive_app, hide password from ps (if sensitive_app does so) and keep all input that starts with
       a space out of history:
          rlwrap -g '^ ' -U sensitive_app --password MySeCrEt

       Wrap gauche (a Scheme interpreter) with a bold blue prompt, enable multi-line editing (using .scm as
       filename extension) and don't consider single quotes as quotes (so that the parentheses in e.g. (print
       'q) match)
          rlwrap -pBlue -m -M .scm -q'"' gosh

       Wrap sqlite3, use the pipeto filter to be able to pipe the output of SQL commands through grep and/or
       less, complete (case-insensitively) on the SQL keywords in 'sql_words'
          rlwrap -a -z pipeto -i -f sql_words sqlite3 contacts.db

       In a shell script, use rlwrap in 'one-shot' mode as a replacement for read
          order=$(rlwrap -pYellow -S 'Your pizza? ' -H past_orders -P Margherita -o cat)

DIRECT MODE AND READLINE MODE

Most simple console commands put your terminal either in "cooked" or in "raw" mode. In cooked mode the
terminal will wait until you press the ENTER key before handing the entire line to the program, in raw
mode every key you press is handed down immediately. In cooked mode you generally can use the backspace
key, but not the arrow keys, to edit your input.

When you rlwrap command, rlwrap will run it a in a separate session, under its own (controlling)
"pseudo-terminal" (pty), and monitor this pty to see whether it is in raw, or in cooked mode. In the
first case, rlwrap will copy all input and output directly between command and your terminal ("direct
mode"). In the second case, rlwrap will use readline to edit your input ("readline mode"), and monitor
command's output - every last line that doesn't end with a newline is a potential prompt. How it handles
such a candidate prompt depends on its being in "patient" or "impatient" mode, see below.

Simple console commands use cooked mode whenever they want whole input lines, and raw mode when they want
single keypresses. Those are the progams for which rlwrap is most useful. More sophisticated commands
have their own line editor and hence use raw mode all the time. With those commands, rlwrap will appear
to "do nothing". Therefore, if rlwrap is in direct mode when the user presses ENTER for the first time
it will give a warning that it needs --always-readline to do anything at all (warnings can be suppressed
with the -n option)

PATIENT, IMPATIENT AND CONFIDENT MODE

       If command writes a lot of output, it tends to be written (and read) in "chunks". Not all chunks will end
       with  a  newline,  and  we  need to distinguish their last lines ("candidate prompts") from real prompts,
       especially if we want to re-write ("cook") prompts. rlwrap solves this (almost) by waiting a  little,  to
       see  if  there  is  more  to  come. "A little" is 40 msec by default, but this can be changed with the -w
       option.  Normally rlwrap writes the candidate prompt as soon as it  is  received,  replacing  it  with  a
       "cooked"  version  after  the  wait time. This is called "impatient" mode. If you don't like the flashing
       effect (which can become annoying when you "cook" the prompt heavily) you  can  put  rlwrap  in  "patient
       mode"  by  specifying  a  negative value with -w (e.g. -w -40). Rlwrap will then hold back the prompt and
       only print if after cooking.  If prompts always match some regular expression you can specify  "confident
       mode"  with  --only-cook='!<regexp>'  (note the exclamation mark).  Then all candidate prompts that match
       (and only those) will be cooked immediately. They  will,  however,  not  be  "uncooked"  if  more  output
       arrives, which can happen if they weren't prompts after all. Confident mode doesn't work  with a negative
       value for the -w option.

COOKING PROMPTS

       If  and when rlwrap decides that it has a prompt, it will perform a number of actions on it, depending on
       the given options: filtering (-z), substituting (-S) and colouring (-p), in  this  order.  The  resulting
       "cooked" prompt is then printed (after erasing the "raw" prompt, if necessary)

SPECIAL KEYS AND BINDABLE COMMANDS

Control + O
Accept the current line, but don't put it in the history list. This action has a readline command
name rlwrap-accept-line-and-forget

Control + ^
Use an external editor (see RLWRAP_EDITOR below) to edit the current input (this will only work if
the -m option is set). This action has a readline command name rlwrap-call-editor

(Not currently bound)
Any key (or key sequence, see below) can be bound to the readline command rlwrap-direct-keypress.
This key (or keys) will then always be sent directly to command, even when rlwrap is not in direct
mode.

(Not currently bound)
Any key or key combination can be bound to the readline command rlwrap-direct-prefix. This makes
it possible to define multi-key direct keypresses by defining their first key(s) as a 'direct
prefix'

(Not currently bound)
Any key can be bound to the readline command rlwrap-hotkey. This key will then cause the current
input line and the current history to be filtered (cf. RlwrapFilter(3pm)) through the current
filter (hence be a no-op when there is no filter), which then can re-write the input line, move
the cursor and update the history. After that, the user can still edit the resulting input.

(Not currently bound)
rlwrap-hotkey-without-history acts like rlwrap-hotkey, but the history (which can be quite large)
is not passed to the filter. This is more efficient if the filter wouldn't do anything useful with
the history anyway.

The special keys were chosen for no other reason than that they are not currently bound to any readline
action. If you don't like them, (or your window manager swallows them) they (and the other 4 commands)
can be re-bound more sensibly by including lines like the following in your ~/.inputrc:

"\M-\C-m": rlwrap-accept-line-and-forget # ESC-ENTER to accept but keep out of history
"\C-x": rlwrap-call-editor # CTRL-x e to edit (multi-line) input in editor of your choice
$if erl # (only) for the Erlang shell:
"\C-g": rlwrap-direct-keypress # pass CTRL-g directly to enter 'user switch' command
$endif
"\C-t": rlwrap-direct-prefix # make it possible to define direct keypresses that start with CTRL-t ...
"\C-tx": rlwrap-direct-keypress # ... in that case: pass CTRL-t + x directly.
"\C-y": rlwrap-hotkey-without-history # CTRL-y to filter input line (and e.g. insert X selection)

cf. the readline(3) manpage. (NB: take care to not use keys that are already caught by your window
manager, or by the terminal driver, like CTRL+S, as rlwrap will never see those)

ENVIRONMENT

       RLWRAP_HOME:
              directory in which the history and completion files are kept.

       RLWRAP_EDITOR (or else EDITOR, or else VISUAL):
              editor to use for multi-line input (and rlwrap-edit-history). Example:

           export RLWRAP_EDITOR="vi +%L"
           export RLWRAP_EDITOR="vim '+call cursor(%L,%C)'"
           export RLWRAP_EDITOR="emacs +%L:%C %F"

       The first example above is the default; %L and %C are replaced by line and column  numbers  corresponding
       to the cursor position in rlwrap's edit buffer, %F is replaced by name of the (temporary) file.  If %F is
       not used, this name is put after the (expanded) $RLWAP_EDITOR

       RLWRAP_FILTERDIR:
              Any  executable  along  your  PATH  can in theory be used as a filter, but because filters have to
              follow a rather outlandish protocol (cf. RlwrapFilter  (3))  it  is  a  good  idea  to  keep  them
              separate.  This  is  why  rlwrap  adds  a  special  filter directory in front of $PATH just before
              launching a filter. By default, this is /usr/share/rlwrap/filters, but $RLWRAP_FILTERDIR  is  used
              instead, if set.

SIGNALS

       A  number  of  signals  are  forwarded  to  command:  HUP INT QUIT USR1 USR2 TERM and (by way of resizing
       command's terminal) WINCH. Some care is taken to handle TSTP (usually a  result  of  a  CTRL-Z  from  the
       terminal)  sensibly  -  for example, after suspending rlwrap in the middle of a line edit, continuing (by
       typing 'fg') will land you at the exact spot where you suspended it.

       A filter can be used to modify/ignore signals, or send output "out of band" to the rlwrapped command.

       Filters (except those that filter signals) that take more than 1 second to respond can be interrupted  by
       a CTRL-C from the terminal (although rlwrap will not survive this)

       If command changes the keystrokes that send a particular signal from the keyboard (like emacs, which uses
       CTRL-G  instead of CTRL-C) rlwrap will do the same (but only after the next keystroke - use the --polling
       option to make rlwrap more transparent in this respect)

       When command is killed by a signal, rlwrap will clean up,  reset  its  signal  handlers  an  then  commit
       suicide by sending the same signal to itself.  This means that your shell sees the same exit status as it
       would have seen without rlwrap.

REDIRECTION

       When  the  standard  input  is not a terminal (or when run inside an emacs buffer), editing input doesn't
       make sense, so rlwrap will ignore all options and simply execute command in place of itself. When  stdout
       (or  stderr)  is  not  a  terminal,  rlwrap will re-open it to /dev/tty (the users terminal) after it has
       started command, so that command's output is redirected as expected, but keyboard input and rlwrap  error
       messages are still visible.

       The upshot of this is that rlwrap command behaves more or less like command when redirecting.

EXIT STATUS

       non-zero  after a rlwrap error, or else command's exit status. rlwrap will always leave the terminal in a
       tidy state, even after a crash.

FILES

       rlwrap expects its history and completion files in $RLWRAP_HOME, but uses .dotfiles in  the  user's  home
       directory  if  this  variable  is  not  set.  This  will  quickly become messy if you use rlwrap for many
       different commands.

       $RLWRAP_HOME/command_history, ~/.command_history
              History for command (remember that command may be overridden by the --command-name (or -C) option)

       $RLWRAP_HOME/command_completions, ~/.command_completions
              Per-user completion word list for command. rlwrap never writes into this list, but one can use  -l
              logfile  and then -f logfile to simulate the effect of a -r option that works across invocations.

       /usr/share/rlwrap/completions/command
              System-wide  completion  word  list  for  command.  This  file  is  only consulted if the per-user
              completion word list is not found.

       $INPUTRC, ~/.inputrc
              Individual readline initialisation file (See  readline  (3)  for  its  format).  rlwrap  sets  its
              application  name  to  command  (this  can  be  overridden  by  the -C option), enabling different
              behaviours for different commands.  One could e.g. put the following lines in ~/.inputrc:

                 $if coqtop
                     set show-all-if-ambiguous On
                 $endif

              making rlwrap show all completions whenever it runs coqtop

BUGS and LIMITATIONS

       Though it is flexible, delivers the goods (readline functionality), and adheres to the Unix  "many  small
       tools" paradigm, rlwrap is a kludge. It doesn't know anything about command's internal state, which makes
       context-sensitive  completion  impossible. Using the GNU Readline library from within command is still by
       far the best option.

       Also, as "it takes two to tango" there is no way for  rlwrap  to  synchronise  its  internal  state  with
       command,  resulting  in a number of subtle race conditions, where e.g. command may have changed the state
       of its terminal before rlwrap has read command output that was written before the state change. You  will
       notice  these  races  especially  on a busy machine and with heavy "cooking" and filtering, when suddenly
       (and unpredictably) prompts or command output are garbled or incorrectly coloured.

       rlwrap can try, but often fails to, handle prompts that contain  control  characters  (prompts,  and  the
       effect  of -A and -t, can be analysed by the filter dissect_prompt). If  -A (--ansi-colour-aware) doesn't
       help, a filter may be needed to clean up the prompt.  Specifying --set-term-name with a simpler, of  even
       dumb, terminal may also help.

VERSION

       This manpage documents rlwrap version 0.46.1

AUTHORS

       The  GNU Readline library (written by Brian Fox and Chet Ramey) does all the hard work behind the scenes,
       the pty-handling code (written by  Geoff  C.  Wing)  was  taken  practically  unchanged  from  rxvt,  and
       completion  word lists are managed by Damian Ivereigh's libredblack library. The rest was written by Hans
       Lub (hanslub42@gmail.com).