`Interact` not working as expected in bash/expect scripting
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In order to provision an embedded device (i.e. writing images to flash) a series of very well known commands have to be entered during the boot stage. The algorithm is something like:
- Capture a bootloader shell by entering any key during boot
- Flash image A
- Flash image B
- ...
- Continue Boot (with new images)
Since we must first capture the bootloader shell at a certain point in the boot process I figured application of an expect
script would solve this problem nicely. I also would like to mix some other bash commands for implementing the logic regarding which device node to connect to, etc. What I came up with (expect portion only) is the following:
#!/bin/bash
DEVICE=...
FLASH_CMD_A=...
#Other bash stuff
expect <<SCRIPT
set timeout 5
spawn plink -serial -sercfg 115200,8,n,1 $DEVICE
expect "Hit any key to stop autoboot"
sleep 1
send "r"
expect "=>"
sleep 1
send "$FLASH_CMD_An"
interact
SCRIPT
echo "Done!"
What I am observing is: The first expect line is properly being captured, the sleep is working, and the newline appears to be being sent. The next expect (capturing the prompt) and its corresponding sleep also appears to be working. The send command ($FLASH_CMD_A) gets printed to the terminal with lots of white spaces between words, but it seems to be working also.
The biggest problem is that the interact
does not appear to be doing anything. Once the second expect/send is executed I am dropped back to a bash shell having never even seen "Done!" printed to stdout. I also tried the interact syntax:
interact
"=>"
send "r"
exp_continue
But that did not work at all. The prompt was never captured and the script just exited immediately as if the interact
statement were not there at all. Any ideas on what I may be doing wrong?
I have:
expect -v
expect version 5.45
Although the commands seem to be being passed to the device I cannot be sure. Once I am dropped back to a bash shell all output from the device following those commands is lost. However, if I run my script a second time expect seems to dump its text buffer (expect_out
?) and exit immediately. Interestingly, the output I was expecting from the previously sent commands is contained within this buffer dump.
As an aside: I tried this same script inside an VM environment and none of the "expect"ed statements were being captured; all input was printed to stdout and passed through.
arch-linux scripting boot-loader expect
add a comment |
In order to provision an embedded device (i.e. writing images to flash) a series of very well known commands have to be entered during the boot stage. The algorithm is something like:
- Capture a bootloader shell by entering any key during boot
- Flash image A
- Flash image B
- ...
- Continue Boot (with new images)
Since we must first capture the bootloader shell at a certain point in the boot process I figured application of an expect
script would solve this problem nicely. I also would like to mix some other bash commands for implementing the logic regarding which device node to connect to, etc. What I came up with (expect portion only) is the following:
#!/bin/bash
DEVICE=...
FLASH_CMD_A=...
#Other bash stuff
expect <<SCRIPT
set timeout 5
spawn plink -serial -sercfg 115200,8,n,1 $DEVICE
expect "Hit any key to stop autoboot"
sleep 1
send "r"
expect "=>"
sleep 1
send "$FLASH_CMD_An"
interact
SCRIPT
echo "Done!"
What I am observing is: The first expect line is properly being captured, the sleep is working, and the newline appears to be being sent. The next expect (capturing the prompt) and its corresponding sleep also appears to be working. The send command ($FLASH_CMD_A) gets printed to the terminal with lots of white spaces between words, but it seems to be working also.
The biggest problem is that the interact
does not appear to be doing anything. Once the second expect/send is executed I am dropped back to a bash shell having never even seen "Done!" printed to stdout. I also tried the interact syntax:
interact
"=>"
send "r"
exp_continue
But that did not work at all. The prompt was never captured and the script just exited immediately as if the interact
statement were not there at all. Any ideas on what I may be doing wrong?
I have:
expect -v
expect version 5.45
Although the commands seem to be being passed to the device I cannot be sure. Once I am dropped back to a bash shell all output from the device following those commands is lost. However, if I run my script a second time expect seems to dump its text buffer (expect_out
?) and exit immediately. Interestingly, the output I was expecting from the previously sent commands is contained within this buffer dump.
As an aside: I tried this same script inside an VM environment and none of the "expect"ed statements were being captured; all input was printed to stdout and passed through.
arch-linux scripting boot-loader expect
Try to addexpect eof
afterinteract
– Costas
Jul 11 '16 at 16:44
add a comment |
In order to provision an embedded device (i.e. writing images to flash) a series of very well known commands have to be entered during the boot stage. The algorithm is something like:
- Capture a bootloader shell by entering any key during boot
- Flash image A
- Flash image B
- ...
- Continue Boot (with new images)
Since we must first capture the bootloader shell at a certain point in the boot process I figured application of an expect
script would solve this problem nicely. I also would like to mix some other bash commands for implementing the logic regarding which device node to connect to, etc. What I came up with (expect portion only) is the following:
#!/bin/bash
DEVICE=...
FLASH_CMD_A=...
#Other bash stuff
expect <<SCRIPT
set timeout 5
spawn plink -serial -sercfg 115200,8,n,1 $DEVICE
expect "Hit any key to stop autoboot"
sleep 1
send "r"
expect "=>"
sleep 1
send "$FLASH_CMD_An"
interact
SCRIPT
echo "Done!"
What I am observing is: The first expect line is properly being captured, the sleep is working, and the newline appears to be being sent. The next expect (capturing the prompt) and its corresponding sleep also appears to be working. The send command ($FLASH_CMD_A) gets printed to the terminal with lots of white spaces between words, but it seems to be working also.
The biggest problem is that the interact
does not appear to be doing anything. Once the second expect/send is executed I am dropped back to a bash shell having never even seen "Done!" printed to stdout. I also tried the interact syntax:
interact
"=>"
send "r"
exp_continue
But that did not work at all. The prompt was never captured and the script just exited immediately as if the interact
statement were not there at all. Any ideas on what I may be doing wrong?
I have:
expect -v
expect version 5.45
Although the commands seem to be being passed to the device I cannot be sure. Once I am dropped back to a bash shell all output from the device following those commands is lost. However, if I run my script a second time expect seems to dump its text buffer (expect_out
?) and exit immediately. Interestingly, the output I was expecting from the previously sent commands is contained within this buffer dump.
As an aside: I tried this same script inside an VM environment and none of the "expect"ed statements were being captured; all input was printed to stdout and passed through.
arch-linux scripting boot-loader expect
In order to provision an embedded device (i.e. writing images to flash) a series of very well known commands have to be entered during the boot stage. The algorithm is something like:
- Capture a bootloader shell by entering any key during boot
- Flash image A
- Flash image B
- ...
- Continue Boot (with new images)
Since we must first capture the bootloader shell at a certain point in the boot process I figured application of an expect
script would solve this problem nicely. I also would like to mix some other bash commands for implementing the logic regarding which device node to connect to, etc. What I came up with (expect portion only) is the following:
#!/bin/bash
DEVICE=...
FLASH_CMD_A=...
#Other bash stuff
expect <<SCRIPT
set timeout 5
spawn plink -serial -sercfg 115200,8,n,1 $DEVICE
expect "Hit any key to stop autoboot"
sleep 1
send "r"
expect "=>"
sleep 1
send "$FLASH_CMD_An"
interact
SCRIPT
echo "Done!"
What I am observing is: The first expect line is properly being captured, the sleep is working, and the newline appears to be being sent. The next expect (capturing the prompt) and its corresponding sleep also appears to be working. The send command ($FLASH_CMD_A) gets printed to the terminal with lots of white spaces between words, but it seems to be working also.
The biggest problem is that the interact
does not appear to be doing anything. Once the second expect/send is executed I am dropped back to a bash shell having never even seen "Done!" printed to stdout. I also tried the interact syntax:
interact
"=>"
send "r"
exp_continue
But that did not work at all. The prompt was never captured and the script just exited immediately as if the interact
statement were not there at all. Any ideas on what I may be doing wrong?
I have:
expect -v
expect version 5.45
Although the commands seem to be being passed to the device I cannot be sure. Once I am dropped back to a bash shell all output from the device following those commands is lost. However, if I run my script a second time expect seems to dump its text buffer (expect_out
?) and exit immediately. Interestingly, the output I was expecting from the previously sent commands is contained within this buffer dump.
As an aside: I tried this same script inside an VM environment and none of the "expect"ed statements were being captured; all input was printed to stdout and passed through.
arch-linux scripting boot-loader expect
arch-linux scripting boot-loader expect
edited Aug 1 '16 at 11:13
Jeff Schaller♦
44.5k1162143
44.5k1162143
asked Jul 11 '16 at 16:15
sherrellbcsherrellbc
88831530
88831530
Try to addexpect eof
afterinteract
– Costas
Jul 11 '16 at 16:44
add a comment |
Try to addexpect eof
afterinteract
– Costas
Jul 11 '16 at 16:44
Try to add
expect eof
after interact
– Costas
Jul 11 '16 at 16:44
Try to add
expect eof
after interact
– Costas
Jul 11 '16 at 16:44
add a comment |
1 Answer
1
active
oldest
votes
As a workaround, run the expect script from a file, and not via standard input:
#!/bin/sh
BLAH='echo hi'
ESCRIPT=`mktemp runner.XXXXXXXXXX` || exit 1
# nope
#expect -d - <<SCRIPT
cat >$ESCRIPT <<SCRIPT
set timeout 5
spawn $SHELL
# FIXME whatever your prompt looks like
expect -ex "% "
send -raw "r"
expect -ex "% "
send -- "$BLAHn"
expect -ex "% "
interact
SCRIPT
expect -d $ESCRIPT
echo alas poor $SHELL I knew him well a man of infinit
# and probably also `trap` in the event this code gets whapped with an INT
# or something...
rm $ESCRIPT
add a comment |
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1 Answer
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active
oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
As a workaround, run the expect script from a file, and not via standard input:
#!/bin/sh
BLAH='echo hi'
ESCRIPT=`mktemp runner.XXXXXXXXXX` || exit 1
# nope
#expect -d - <<SCRIPT
cat >$ESCRIPT <<SCRIPT
set timeout 5
spawn $SHELL
# FIXME whatever your prompt looks like
expect -ex "% "
send -raw "r"
expect -ex "% "
send -- "$BLAHn"
expect -ex "% "
interact
SCRIPT
expect -d $ESCRIPT
echo alas poor $SHELL I knew him well a man of infinit
# and probably also `trap` in the event this code gets whapped with an INT
# or something...
rm $ESCRIPT
add a comment |
As a workaround, run the expect script from a file, and not via standard input:
#!/bin/sh
BLAH='echo hi'
ESCRIPT=`mktemp runner.XXXXXXXXXX` || exit 1
# nope
#expect -d - <<SCRIPT
cat >$ESCRIPT <<SCRIPT
set timeout 5
spawn $SHELL
# FIXME whatever your prompt looks like
expect -ex "% "
send -raw "r"
expect -ex "% "
send -- "$BLAHn"
expect -ex "% "
interact
SCRIPT
expect -d $ESCRIPT
echo alas poor $SHELL I knew him well a man of infinit
# and probably also `trap` in the event this code gets whapped with an INT
# or something...
rm $ESCRIPT
add a comment |
As a workaround, run the expect script from a file, and not via standard input:
#!/bin/sh
BLAH='echo hi'
ESCRIPT=`mktemp runner.XXXXXXXXXX` || exit 1
# nope
#expect -d - <<SCRIPT
cat >$ESCRIPT <<SCRIPT
set timeout 5
spawn $SHELL
# FIXME whatever your prompt looks like
expect -ex "% "
send -raw "r"
expect -ex "% "
send -- "$BLAHn"
expect -ex "% "
interact
SCRIPT
expect -d $ESCRIPT
echo alas poor $SHELL I knew him well a man of infinit
# and probably also `trap` in the event this code gets whapped with an INT
# or something...
rm $ESCRIPT
As a workaround, run the expect script from a file, and not via standard input:
#!/bin/sh
BLAH='echo hi'
ESCRIPT=`mktemp runner.XXXXXXXXXX` || exit 1
# nope
#expect -d - <<SCRIPT
cat >$ESCRIPT <<SCRIPT
set timeout 5
spawn $SHELL
# FIXME whatever your prompt looks like
expect -ex "% "
send -raw "r"
expect -ex "% "
send -- "$BLAHn"
expect -ex "% "
interact
SCRIPT
expect -d $ESCRIPT
echo alas poor $SHELL I knew him well a man of infinit
# and probably also `trap` in the event this code gets whapped with an INT
# or something...
rm $ESCRIPT
answered Jul 11 '16 at 18:15
thrigthrig
25.3k23257
25.3k23257
add a comment |
add a comment |
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Try to add
expect eof
afterinteract
– Costas
Jul 11 '16 at 16:44