05-29-2017
If you want to script interaction with a program expecting human input, bash and most other shells are very bad at that. Pipes are poor substitutes for the interactive terminal the program is obviously expecting, they tend to deadlock with each process waiting for the other and no way to notify each other of said fact.
If your interaction is any more complicated than typing one number and hitting enter, you might look into the expect language, which is designed for these sort of problems. It will allocate a PTY which allows it to control the program it's communicating with asynchronously without all the piping and redirection.
Last edited by Corona688; 05-29-2017 at 03:15 PM..
10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
Working in a bash environment, in the following example, how do I direct the error message that putting in an invalid flag (-j for example) would normally produce to dev/null?
while getopts "abcd" opt
do
case "$opt" in
i) a etc ;;
r) b etc ;;
f) c etc ;;
v) d... (7 Replies)
Discussion started by: Sniper Pixie
7 Replies
2. Shell Programming and Scripting
can you redirect STDIN with command arguments?
I have tried this approach:
# ./script -option <argument1> <argument2> 0<$2
# $2: ambiguous redirect
Is this possible? (4 Replies)
Discussion started by: prkfriryce
4 Replies
3. Shell Programming and Scripting
Consider:
#!/bin/sh
#this is a shell script in sh (bourne)
grep missingfile 2>errout.txt
It works from the command line, but keeps producing errors from the script. So how do I redirect in a bash shell...or bourne? (3 Replies)
Discussion started by: lumix
3 Replies
4. Programming
For windows was pretty simple to redirect the std in a and out of a
child process for "cmd.exe " command prompt terminal to a socket using connected pipes passed to a new process in the STARTUPINFO structure.
BOOL b = ::CreatePipe((LPHANDLE)h_stdInRead,(LPHANDLE)hsdtInWriteTmp, &SecAttrib,... (1 Reply)
Discussion started by: gyula
1 Replies
5. Shell Programming and Scripting
Hi:
I have the next script on ksh
#!/usr/bin/ksh
cd $FUENTES
qdesign <<-!
\$/opt/cognos/ph843e/bin/qtp <<-!
\$/opt/cognos/ph843e/bin/quiz <<-!
!
!
!
This script is very simple, i want to nest three process quiz into qtp, and this into qdesign.
When I run it , i receive the... (5 Replies)
Discussion started by: ct2marer
5 Replies
6. UNIX for Advanced & Expert Users
Hi:
I have the next script on ksh
#!/usr/bin/ksh
cd $FUENTES
qdesign <<-!
\$/opt/cognos/ph843e/bin/qtp <<-!
\$/opt/cognos/ph843e/bin/quiz <<-!
!
!
!
This script is very simple, i want to nest three process quiz into qtp, and this into qdesign.
When I run it , i receive the next... (2 Replies)
Discussion started by: ct2marer
2 Replies
7. Shell Programming and Scripting
I am unable to use STDIn redirection with < (commands)
When I do the following, both approaches work and give the same results:
1.
$ printf "aaa\nbbb\n" > file1
$ printf "111\n222\n" > file2
$ cat file1 file2
aaa
bbb
111
2222.
$ cat <(printf "aaa\nbbb\n") <(printf "111\n222\n")
aaa... (8 Replies)
Discussion started by: metaltree
8 Replies
8. Shell Programming and Scripting
Looking for the proper way to bring a string into the stdin. I have a string that I would like to grep and awk. Each have to be run separately, not piped together. So far, the only way I could figure out how is to echo the string and pipe it:
echo 'This is my string' | grep my (3 Replies)
Discussion started by: Panman82
3 Replies
9. UNIX for Advanced & Expert Users
I want to differentiate the STDOUT and STDERR messages in my terminal .
If a script or command is printing a message in terminal I want to differentiate by colors,
Is it possible ?
Example:
$date
Wed Jul 27 12:36:50 IST 2011
$datee
bash: datee: command not found
$alias ls
alias... (2 Replies)
Discussion started by: ungalnanban
2 Replies
10. Shell Programming and Scripting
Hi, I'm running a program (Python) whose output I would like to redirect to a log. But the program calls a library (that I cannot change), which outputs all sorts of useless information.
I would like to redirect all output from my Python program into this log, except output that matches the... (7 Replies)
Discussion started by: rswindle
7 Replies
SCRIPT(1) User Commands SCRIPT(1)
NAME
script - make typescript of terminal session
SYNOPSIS
script [options] [file]
DESCRIPTION
script makes a typescript of everything displayed on your terminal. It is useful for students who need a hardcopy record of an interactive
session as proof of an assignment, as the typescript file can be printed out later with lpr(1).
If the argument file is given, script saves the dialogue in this file. If no filename is given, the dialogue is saved in the file type-
script.
OPTIONS
-a, --append
Append the output to file or to typescript, retaining the prior contents.
-c, --command command
Run the command rather than an interactive shell. This makes it easy for a script to capture the output of a program that behaves
differently when its stdout is not a tty.
-e, --return
Return the exit code of the child process. Uses the same format as bash termination on signal termination exit code is 128+n.
-f, --flush
Flush output after each write. This is nice for telecooperation: one person does `mkfifo foo; script -f foo', and another can
supervise real-time what is being done using `cat foo'.
--force
Allow the default output destination, i.e. the typescript file, to be a hard or symbolic link. The command will follow a symbolic
link.
-q, --quiet
Be quiet (do not write start and done messages to standard output).
-t[file], --timing[=file]
Output timing data to standard error, or to file when given. This data contains two fields, separated by a space. The first field
indicates how much time elapsed since the previous output. The second field indicates how many characters were output this time.
This information can be used to replay typescripts with realistic typing and output delays.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
NOTES
The script ends when the forked shell exits (a control-D for the Bourne shell (sh(1)), and exit, logout or control-d (if ignoreeof is not
set) for the C-shell, csh(1)).
Certain interactive commands, such as vi(1), create garbage in the typescript file. script works best with commands that do not manipulate
the screen, the results are meant to emulate a hardcopy terminal.
It is not recommended to run script in non-interactive shells. The inner shell of script is always interactive, and this could lead to
unexpected results. If you use script in the shell initialization file, you have to avoid entering an infinite loop. You can use for
example the .profile file, which is read by login shells only:
if test -t 0 ; then
script
exit
fi
You should also avoid use of script in command pipes, as script can read more input than you would expect.
ENVIRONMENT
The following environment variable is utilized by script:
SHELL If the variable SHELL exists, the shell forked by script will be that shell. If SHELL is not set, the Bourne shell is assumed.
(Most shells set this variable automatically).
SEE ALSO
csh(1) (for the history mechanism), scriptreplay(1)
HISTORY
The script command appeared in 3.0BSD.
BUGS
script places everything in the log file, including linefeeds and backspaces. This is not what the naive user expects.
script is primarily designed for interactive terminal sessions. When stdin is not a terminal (for example: echo foo | script), then the
session can hang, because the interactive shell within the script session misses EOF and script has no clue when to close the session. See
the NOTES section for more information.
AVAILABILITY
The script command is part of the util-linux package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils
/util-linux/>.
util-linux June 2014 SCRIPT(1)