So I am trying to debug a program which requires the user to input some text through the terminal:
$ echo 'here is the text' | ./program
How do I simulate that input in GDB?
You can run the program with input redirected:
echo 'here is the text' > intput.txt
gdb ./program
(gdb) run < intput.txt
You can do using --args option giving program executable followed by arguments as below,
% gdb --args ./program arg1 arg2
Related
How can I use the netcat program for bidirectional communication with a networked postscript printer? Postscript programs frequently send information to the STDOUT and that is difficult to capture over the network. I need bidirectional communication with the printer 9100 port. My answer is below. Does anybody know of a better way?
The netcat program can be used for bidirectional communication with a postscript printer.
I have been using some simple programs to send print jobs directly to a network postscript printer and haven't gotten any return info from the printer until now. I like to communicate directly with the printer instead of sending jobs to a spooler.
There is a little information a few places about printing with netcat just very sparse so I am making this report.
My printer is a Xerox 6500n connected to a router by ethernet cable. I can send postscript programs or pdf files directly to the printer in a variety of ways. Sometimes I want to get answers from the printer and so have a test program to use the printer to convert the input using 'pathforall' and send back the answer. The netcat does this nicely:
nc -n 192.168.1.111 9100 < pathforall.ps
I then get the desired response. This has been checked and is similar to ghostscript output only slightly off for some reason:
$ nc -v -w 5 -n 192.168.1.111 9100 < pathforall.ps
192.168.1.111 9100 (hp-pdl-datastr) open
28.6998 12.2999 moveto
28.6998 9.29996 28.3998 8.09995 25.2998 6.59998 curveto
24.3998 6.09998 21.2999 4.79999 19.0999 4.79999 curveto
15.3999 4.79999 12.4999 7.89996 12.4999 12.5999 curveto
12.4999 12.7999 lineto
12.4999 16.1999 13.5999 21.7999 28.6998 26.7999 curveto
closepath
$ gs pathforall.ps
GPL Ghostscript 9.50 (2019-10-15)
Copyright (C) 2019 Artifex Software, Inc. All rights reserved.
This software is supplied under the GNU AGPLv3 and comes with NO WARRANTY:
see the file COPYING for details.
Loading Times-Roman font from /usr/share/ghostscript/fonts/Times-Roman.pfa... 4824712 3114962 3833824 2546359 1 done.
28.6184 12.2615 moveto
28.6184 9.27632 28.3224 8.07977 25.2262 6.57484 curveto
24.3257 6.08141 21.2418 4.78618 19.0461 4.78618 curveto
15.3577 4.78618 12.4589 7.8824 12.4589 12.5576 curveto
12.4589 12.7673 lineto
12.4589 16.1472 13.5567 21.7352 28.6184 26.7188 curveto
28.6184 12.2615 lineto
closepath
The netcat allows me to communicate with my printer similar to ghostscript except I don't have the executive mode working yet. Also, be sure to include a 'flush' command in the postscript to get the entire answer sent back.
This can be used for many purposes to get information from the printer.
EDIT: Here is a simple test to see if the printer STDOUT is getting back to the computer:
%!
(Hello World\n) print flush
EDIT3: Postscript executive mode works using telnet for the Xerox 6500n as suggested by luser droog. See comments below.
Here is a bash /dev/tcp alternative for printing without netcat.
This sends to a network PostScript printer using bash if built with --enable-net-redirections. This works with my Void bash and with my Xerox Phaser 6500n and switches between PJL and PostScript. Testing results with other printers would be helpful.
#!/bin/bash
#
# ++++ driverless postscript printing ++++
# bash needs --enable-net-redirections build option
#
# for postscript programs with postscript printer only
#
# bash escape is \033 or \e or \E or \x1B
exec 5<>/dev/tcp/192.168.1.111/9100 || exit 1 # change ip as needed
{
echo -e "\E%-12345X#PJL" # PJL entrance
echo #PJL ECHO "$(date)"
echo #PJL ECHO "setting up printer ..."
echo #PJL COMMENT Change Printer Settings
echo #PJL SET COPIES = 1 # modify environment settings
echo #PJL SET MANUALFEED = off
echo #PJL ECHO "Starting PostScript Program ..."
echo #PJL ENTER LANGUAGE = POSTSCRIPT
echo "%!" # optional
cat "$1" || echo -E "(Hello World\n) print flush" # if input.ps missing
echo -e "\004" # ctrl-D for end of file
echo -e "\e%-12345X#PJL" # back to PJL
echo #PJL ECHO "Finished PostScript Program."
echo #PJL RESET # unset modified environment settings
echo #PJL ECHO BYE.
echo -e "\033%-12345X" # PJL universal exit
} >&5 # send to printer
while read -t 122 -r LINE # timeout after 122 seconds of silence
do
echo "$LINE"
if [[ "$LINE" =~ #PJL\ ECHO\ BYE. ]]; then break; fi
done <&5
echo "Finished reading printer"
exec 5>&- # close
exec 5<&- # close both
exit 0
Here is the result in my terminal. Be sure to send a file like "print.sh input.ps" or this will happen:
$ ./print.sh
cat: '': No such file or directory
#PJL ECHO Mon 20 Apr 2020 07:10:03 AM PDT
#PJL ECHO setting up printer ...
#PJL ECHO Starting PostScript Program ...
Hello World
#PJL ECHO Finished PostScript Program.
#PJL ECHO BYE.
Finished reading printer
UPDATE: I have added this here: github
How to write expect script which executes command and prints just the command's output?
I've tried various things but none works, e.g.
#!/usr/bin/expect
log_user 0
spawn bash
send "echo 1\r"
log_user 1
expect "1"
log_user 0
send "exit\r"
expect eof
Gives in output:
echo 1
While I need just "1" . I hope somebody knows simple solution how to fix my example
Capturing the output from sent commands is a bit of a pain in expect.
Here's a more general case that does not rely on the log_user setting, it captures the output with a regular expression:
#!/usr/bin/expect
log_user 0
spawn bash
# set the prompt to a known value
send "PS1='>'\r"
expect -re {>$}
# send a command: we don't know what the output is going to be
send "echo \$RANDOM\r"
# capture the portion of the output that occurs just before the prompt
expect -re "\r\n(.*?)\r\n>$"
puts "output is: $expect_out(1,string)"
send "exit\r"
expect eof
A thought just occurred to me: if the command does not require any interaction, then expect is overkill: just use exec
set output [exec bash -c {echo $RANDOM}]
Ok, it looks following script does (at least similar to) what I need:
log_user 0
spawn bash
expect "#" {} "\\\$" {}
send -- "echo AA\r"
expect -- "echo AA\r" {}
log_user 1
expect -- "AA"
log_user 0
send -- "exit\r"
expect eof
I'm entirely new to using bash and Xcode build scripts and so my code is probably a jungle full of errors.
The idea here is to trigger the script below which will scrape the directory that it is saved in for any .js automation scripts. It will then send these scripts to instruments to be run one at a time. I found some nifty code that created time stamped files and so I used that to create a more meaningful storage system.
#!/bin/bash
# This script should run all (currently only one) tests, independently from
# where it is called from (terminal, or Xcode Run Script).
# REQUIREMENTS: This script has to be located in the same folder as all the
# UIAutomation tests. Additionally, a *.tracetemplate file has to be present
# in the same folder. This can be created with Instruments (Save as template...)
# The following variables have to be configured:
#EXECUTABLE="Plans.app"
# Find the test folder (this script has to be located in the same folder).
ROOT="$( cd -P "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
# Prepare all the required args for instruments.
TEMPLATE=`find $ROOT -name '*.tracetemplate'`
#EXECUTABLE=`find ~/Library/Application\ Support/iPhone\ Simulator | grep "${EXECUTABLE}$"`
echo "$BUILT_PRODUCTS_DIR"
echo "$PRODUCT_NAME"
EXECUTABLE="${BUILT_PRODUCTS_DIR}/${PRODUCT_NAME}.app/"
SCRIPTS=`find $ROOT -name '*.js'`
# Prepare traces folder
TRACES="${ROOT}/Traces/`date +%Y-%m-%d_%H-%M-%S`"
mkdir -p "$TRACES"
printf "\n" >> "$ROOT/results.log"
echo `date +%Y-%m-%d_%H-%M-%S` >> "$ROOT/results.log"
# Get the name of the user we should use to run Instruments.
# Currently this is done, by getting the owner of the folder containing this script.
USERNAME=`ls -l "${ROOT}/.." | grep \`basename "$ROOT"\` | awk '{print $3}'`
# Bring simulator window to front. Depending on the localization, the name is different.
osascript -e 'try
tell application "iPhone Simulator" to activate
on error
tell application "iOS Simulator" to activate
end try'
# Prepare an Apple Script that promts for the password.
PASS_SCRIPT="tell application \"System Events\"
activate
display dialog \"Password for user $USER:\" default answer \"\" with hidden answer
text returned of the result
end tell"
# Run all the tests.
for SCRIPT in $SCRIPTS; do
echo -e "\nRunning test script $SCRIPT"
TESTC="sudo -u ${USER} xcrun instruments -l -c -t ${TEMPLATE} ${EXECUTABLE} -e UIARESULTSPATH ${TRACES}/${TRACENAME} -e UIASCRIPT ${SCRIPT} >> ${ROOT}/results.log"
#echo "$COMMAND"
echo "Executing command $TESTC" >> "$ROOT/results.log"
echo "here $TESTC" >> "$ROOT/results.log"
OUTPUT=$(TESTC)
echo $OUTPUT >> "$ROOT/results.log"
echo "Finished logging" >> "$ROOT/results.log"
SCRIPTNAME=`basename "$SCRIPT"`
TRACENAME=`echo "$SCRIPTNAME" | sed 's_\.js$_.trace_g'`
for i in $(ls -A1t $PWD | grep -m 1 '.trace')
do
TRACEFILE="$PWD/$i"
done
if [ -e $TRACEFILE ]; then
mv "$TRACEFILE" "${TRACES}/${TRACENAME}"
fi
if [ `grep " Fail: " results.log | wc -l` -gt 0 ]; then
echo "Test ${SCRIPTNAME} failed. See trace for details."
open "${TRACES}/${TRACENAME}"
exit 1
break
fi
done
rm results.log
A good portion of this was taken from another Stack Overflow answer but because of the repository setup that I'm working with I needed to keep the paths abstract and separate from the root folder of the script. Everything seems to work (although probably not incredibly efficiently) except for the actual xcrun command to launch instruments.
TESTC="sudo -u ${USER} xcrun instruments -l -c -t ${TEMPLATE} ${EXECUTABLE} -e UIARESULTSPATH ${TRACES}/${TRACENAME} -e UIASCRIPT ${SCRIPT} >> ${ROOT}/results.log"
echo "Executing command $TESTC" >> "$ROOT/results.log"
OUTPUT=$(TESTC)
This is turned into the following by whatever black magic Bash runs on:
sudo -u Braains xcrun instruments -l -c -t
/Users/Braains/Documents/Automation/AppName/TestCases/UIAutomationTemplate.tracetemplate
/Users/Braains/Library/Developer/Xcode/DerivedData/AppName-
ekqevowxyipndychtscxwgqkaxdk/Build/Products/Debug-iphoneos/AppName.app/ -e UIARESULTSPATH
/Users/Braains/Documents/Automation/AppName/TestCases/Traces/2014-07-17_16-31-49/ -e
UIASCRIPT /Users/Braains/Documents/Automation/AppName/TestCases/Test-Case_1js
(^ Has inserted line breaks for clarity of the question ^)
The resulting error that I am seeing is:
posix spawn failure; aborting launch (binary ==
/Users/Braains/Library/Developer/Xcode/DerivedData/AppName-
ekqevowxyipndychtscxwgqkaxdk/Build/Products/Debug-iphoneos/AppName.app/AppName).
I have looked all over for a solution to this but I can't find anything because Appium has a similar issue. Unfortunately I don't understand the systems well enough to know how to translate the fixes to Appium to my own code but I imagine it's a similar issue.
I do know that the posix spawn failure is related to threading, but I don't know enough about xcrun to say what's causing the threading issue.
Related info:
- I'm building for the simulator but it'd be great to work on real devices too
- I'm using xCode 5.1.1 and iOS Simulator 7.1
- This script is meant to be run as a build post action script in xCode
- I did get it briefly working once before I broke it and couldn't get it back to the working state. So I think that means all of my permissions are set correctly.
UPDATE: So I've gotten to the root of this problem although I have not found a fix yet. First of all I have no idea what xcrun is for and so I dropped it. Then after playing around I found that my Xcode environment variables are returning the wrong path, probably because of some project setting somewhere. If you copy the Bash command from above but replace Debug-iphoneos with Debug-iphonesimulator the script can be run from the command line and will work as expected.
So for anyone who happens across this the only solution I could find was to hardcode the script for the simulator.
I changed EXECUTABLE="${BUILT_PRODUCTS_DIR}/${PRODUCT_NAME}.app/" to be EXECUTABLE="${SYMROOT}/Debug-iphonesimulator/${EXECUTABLE_PATH}". This is obviously not a great solution but it works for now.
I was following this simple tutorial to try out a simple lua script
http://www.redisgreen.net/blog/2013/03/18/intro-to-lua-for-redis-programmers/
I created a simple hello.lua file with these lines
local msg = "Hello, world!"
return msg
And i tried running simple command
EVAL "$(cat /Users/rsingh/Downloads/hello.lua)" 0
And i am getting this error
(error) ERR Error compiling script (new function): user_script:1: unexpected symbol near '$'
I can't find what is wrong here and i haven't been able to find someone who has come across this.
Any help would be deeply appreciated.
Your problem comes from the fact you are executing this command from an interactive Redis session:
$ redis-cli
127.0.0.1:6379> EVAL "$(cat /path/to/hello.lua)" 0
(error) ERR Error compiling script (new function): user_script:1: unexpected symbol near '$'
Within such a session you cannot use common command-line tools like cat et al. (here cat is used as a convenient way to get the content of your script in-place). In other words: you send "$(cat /path/to/hello.lua)" as a plain string to Redis, which is not Lua code (of course), and Redis complains.
To execute this sample you must stay in the shell:
$ redis-cli EVAL "$(cat /path/to/hello.lua)" 0
"Hello, world!"
If you are coming from windows and trying to run a lua script you should use this format:
redis-cli --eval script.lua
Run this from the folder where your script is located and it will load a multi line file and execute it.
On the off chance that anyone's come to this from Windows instead, I found I had to do a lot of juggling to achieve the same effect. I had to do this:
echo “local msg = 'Hello, world!'; return msg” > hello.lua
for /F "delims=" %i in ('type hello.lua') do #set cmd=%i
redis-cli eval "%cmd%" 0
.. if you want it saved as a file, although you'll have to have all the content on one line. If you don’t just roll the content into a set command
set cmd=“local msg = 'Hello, world!'; return msg”
redis-cli eval "%cmd%" 0
I'm trying to set up a shell script that will start a screen session (or rejoin an existing one) only if it is invoked from an interactive shell. The solution I have seen is to check if $- contains the letter "i":
#!/bin/sh -e
echo "Testing interactivity..."
echo 'Current value of $- = '"$-"
if [ `echo \$- | grep -qs i` ]; then
echo interactive;
else
echo noninteractive;
fi
However, this fails, because the script is run by a new noninteractive shell, invoked as a result of the #!/bin/sh at the top. If I source the script instead of running it, it works as desired, but that's an ugly hack. I'd rather have it work when I run it.
So how can I test for interactivity within a script?
Give this a try and see if it does what you're looking for:
#!/bin/sh
if [ $_ != $0 ]
then
echo interactive;
else
echo noninteractive;
fi
The underscore ($_) expands to the absolute pathname used to invoke the script. The zero ($0) expands to the name of the script. If they're different then the script was invoked from an interactive shell. In Bash, subsequent expansion of $_ gives the expanded argument to the previous command (it might be a good idea to save the value of $_ in another variable in order to preserve it).
From man bash:
0 Expands to the name of the shell or shell script. This is set
at shell initialization. If bash is invoked with a file of com‐
mands, $0 is set to the name of that file. If bash is started
with the -c option, then $0 is set to the first argument after
the string to be executed, if one is present. Otherwise, it is
set to the file name used to invoke bash, as given by argument
zero.
_ At shell startup, set to the absolute pathname used to invoke
the shell or shell script being executed as passed in the envi‐
ronment or argument list. Subsequently, expands to the last
argument to the previous command, after expansion. Also set to
the full pathname used to invoke each command executed and
placed in the environment exported to that command. When check‐
ing mail, this parameter holds the name of the mail file cur‐
rently being checked.
$_ may not work in every POSIX compatible sh, although it probably works in must.
$PS1 will only be set if the shell is interactive. So this should work:
if [ -z "$PS1" ]; then
echo noninteractive
else
echo interactive
fi
try tty
if tty 2>&1 |grep not ; then echo "Not a tty"; else echo "a tty"; fi
man tty :
The tty utility writes the name of the terminal attached to standard
input to standard output. The name that is written is the string
returned by ttyname(3). If the standard input is not a terminal, the
message ``not a tty'' is written.
You could try using something like...
if [[ -t 0 ]]
then
echo "Interactive...say something!"
read line
echo $line
else
echo "Not Interactive"
fi
The "-t" switch in the test field checks if the file descriptor given matches a terminal (you could also do this to stop the program if the output was going to be printed to a terminal, for example). Here it checks if the standard in of the program matches a terminal.
Simple answer: don't run those commands inside ` ` or [ ].
There is no need for either of those constructs here.
Obviously I can't be sure what you expected
[ `echo \$- | grep -qs i` ]
to be testing, but I don't think it's testing what you think it's testing.
That code will do the following:
Run echo \$- | grep -qs i inside a subshell (due to the ` `).
Capture the subshell's standard output.
Replace the original ` ` expression with a string containing that output.
Pass that string as an argument to the [ command or built-in (depending on your shell).
Produce a successful return code from [ only if that string was nonempty (assuming the string didn't look like an option to [).
Some possible problems:
The -qs options to grep should cause it to produce no output, so I'd expect [ to be testing an empty string regardless of what $- looks like.
It's also possible that the backslash is escaping the dollar sign and causing a literal 'dollar minus' (rather than the contents of a variable) to be sent to grep.
On the other hand, if you removed the [ and backticks and instead said
if echo "$-" | grep -qs i ; then
then:
your current shell would expand "$-" with the value you want to test,
echo ... | would send that to grep on its standard input,
grep would return a successful return code when that input contained the letter i,
grep would print no output, due to the -qs flags, and
the if statement would use grep's return code to decide which branch to take.
Also:
no backticks would replace any commands with the output produced when they were run, and
no [ command would try to replace the return code of grep with some return code that it had tried to reconstruct by itself from the output produced by grep.
For more on how to use the if command, see this section of the excellent BashGuide.
If you want to test the value of $- without forking an external process (e.g. grep) then you can use the following technique:
if [ "${-%i*}" != "$-" ]
then
echo Interactive shell
else
echo Not an interactive shell
fi
This deletes any match for i* from the value of $- then checks to see if this made any difference.
(The ${parameter/from/to} construct (e.g. [ "${-//[!i]/}" = "i" ] is true iff interactive) can be used in Bash scripts but is not present in Dash, which is /bin/sh on Debian and Ubuntu systems.)