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Can you interactively modify the terminal reset in 'less'?
Clash Royale CLAN TAG#URR8PPP
up vote
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I usually do not want to reset the terminal when I exit less (that is, I want the screen to continue displaying what I was looking at). Usually, when I'm on a new box and haven't configured it yet, I invoke less, quit, see the screen reset, curse mildly, and rerun with less -X ... On very rare occasions, I remember that the screen is going to reset as soon as I quit, in which case the sequence of events is slightly modified and the mild cursing occurs before I quit, but the overall effect is about the same.
Is there any way to modify a currently running less process so that it will not reset the terminal upon exit?
less terminfo termcap
asked 3 hours ago
William Pursell
2,12911112
add a comment |Â
up vote
1
down vote
favorite
I usually do not want to reset the terminal when I exit less (that is, I want the screen to continue displaying what I was looking at). Usually, when I'm on a new box and haven't configured it yet, I invoke less, quit, see the screen reset, curse mildly, and rerun with less -X ... On very rare occasions, I remember that the screen is going to reset as soon as I quit, in which case the sequence of events is slightly modified and the mild cursing occurs before I quit, but the overall effect is about the same.
Is there any way to modify a currently running less process so that it will not reset the terminal upon exit?
less terminfo termcap
asked 3 hours ago
William Pursell
2,12911112
short - no. long - see my answer.
– Thomas Dickey
2 hours ago
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I usually do not want to reset the terminal when I exit less (that is, I want the screen to continue displaying what I was looking at). Usually, when I'm on a new box and haven't configured it yet, I invoke less, quit, see the screen reset, curse mildly, and rerun with less -X ... On very rare occasions, I remember that the screen is going to reset as soon as I quit, in which case the sequence of events is slightly modified and the mild cursing occurs before I quit, but the overall effect is about the same.
Is there any way to modify a currently running less process so that it will not reset the terminal upon exit?
less terminfo termcap
asked 3 hours ago
William Pursell
2,12911112
I usually do not want to reset the terminal when I exit less (that is, I want the screen to continue displaying what I was looking at). Usually, when I'm on a new box and haven't configured it yet, I invoke less, quit, see the screen reset, curse mildly, and rerun with less -X ... On very rare occasions, I remember that the screen is going to reset as soon as I quit, in which case the sequence of events is slightly modified and the mild cursing occurs before I quit, but the overall effect is about the same.
Is there any way to modify a currently running less process so that it will not reset the terminal upon exit?
less terminfo termcap
less terminfo termcap
asked 3 hours ago
William Pursell
2,12911112
asked 3 hours ago
William Pursell
2,12911112
asked 3 hours ago
William Pursell
2,12911112
asked 3 hours ago
William Pursell
2,12911112
asked 3 hours ago
William Pursell
2,12911112
2,12911112
short - no. long - see my answer.
– Thomas Dickey
2 hours ago
add a comment |Â
short - no. long - see my answer.
– Thomas Dickey
2 hours ago
short - no. long - see my answer.
– Thomas Dickey
2 hours ago
short - no. long - see my answer.
– Thomas Dickey
2 hours ago
add a comment |Â
2 Answers
2
active
oldest
votes
up vote
2
down vote
Some terminals (such as xterm) have a menu setting which enable/disables switching to/from alternate screen. Most do not...
By the way (same issue of some/most), if a terminal implements the original xterm 47 code alternate-screen switching, it is possible to switch back into the alternate screen without clearing it. I've noticed some which set TERM=xterm which do not implement this (only implementing the later 1049 code) - ymmv
You can see how the 47 code is used in a normal terminal description by looking at the smcup and rmcup capabilities from
infocmp xterm-old
which shows these items (among others):
rmcup=E[2JE[?47lE8,
smcup=E7E[?47h,
The E[2J in rmcup clears the (alternate) screen before switching back to the normal screen. The E7 and E8 save/restore the cursor position (for the normal screen). If you really wanted to, you could replace those capabilities with whatever xterm-compatible terminal description, omitting the clear-screen part, allowing you to do
tput smcup
tput rmcup
from the command-line and see what was on the alternate screen. It wouldn't be nice (since your command-line would overwrite parts of it), but it might help.
It's not needed in xterm, since xterm has a menu option for switching back/forth. But you might find that approach useful.
Further reading:
Why doesn't the screen clear when running vi? (xterm FAQ)- XTerm Control Sequences
answered 2 hours ago
Thomas Dickey
51.1k593162
add a comment |Â
up vote
2
down vote
use | . cat.
Stepwise: press |, then at the |mark: prompt press ., then at the ! prompt enter cat, then at the |done (press RETURN) prompt press Enter again; when you quit less, the current page we be left on the screen.
If you want the output to be processed as it was by less (with backspace+underscore transformed to underline, non-printable characters shown as <XX>, etc), use less -FX instead of cat.
from the less(1) manpage:
| <m> shell-command
<m> represents any mark letter. Pipes a section of the input
file to the given shell command. The section of the file to be
piped is between the first line on the current screen and the
position marked by the letter. <m> may also be ^ or $ to indi-
cate beginning or end of file respectively. If <m> is . or new-
line, the current screen is piped.
Afterwards, if you want to simply zap the rmcup/smcup alternate screen switching without having to reconfigure again and again every xterm clone, you can use this command:
infocmp | sed 's/[sr]mcup=[^=]*,//g' | tic -
This will write inside ~/.terminfo a terminal description for your current terminal with the codes for alternate screen switching omitted. It should be used in preference to that from /usr/share/terminfo by most programs.
edited 13 mins ago
Jeff Schaller
34.5k951115
answered 2 hours ago
qubert
1934
That prints the file which less is rendering, but it's not the same, e.g., if it contains non-printing characters (and does not affect the reset).
– Thomas Dickey
2 hours ago
@ThomasDickey I hope I addressed your objections in the last revision.
– qubert
2 hours ago
That's better (writing an approximation to the normal screen), though as noted, you can't modify the reset from within less :-)
– Thomas Dickey
2 hours ago
This is ingenious. To make sure I understand what's happening, less writes to the alternate screen and the shell out to cat writes to the normal screen?
– William Pursell
1 hour ago
@WilliamPursell exactly.
– qubert
1 hour ago
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
Some terminals (such as xterm) have a menu setting which enable/disables switching to/from alternate screen. Most do not...
By the way (same issue of some/most), if a terminal implements the original xterm 47 code alternate-screen switching, it is possible to switch back into the alternate screen without clearing it. I've noticed some which set TERM=xterm which do not implement this (only implementing the later 1049 code) - ymmv
You can see how the 47 code is used in a normal terminal description by looking at the smcup and rmcup capabilities from
infocmp xterm-old
which shows these items (among others):
rmcup=E[2JE[?47lE8,
smcup=E7E[?47h,
The E[2J in rmcup clears the (alternate) screen before switching back to the normal screen. The E7 and E8 save/restore the cursor position (for the normal screen). If you really wanted to, you could replace those capabilities with whatever xterm-compatible terminal description, omitting the clear-screen part, allowing you to do
tput smcup
tput rmcup
from the command-line and see what was on the alternate screen. It wouldn't be nice (since your command-line would overwrite parts of it), but it might help.
It's not needed in xterm, since xterm has a menu option for switching back/forth. But you might find that approach useful.
Further reading:
Why doesn't the screen clear when running vi? (xterm FAQ)- XTerm Control Sequences
answered 2 hours ago
Thomas Dickey
51.1k593162
add a comment |Â
up vote
2
down vote
Some terminals (such as xterm) have a menu setting which enable/disables switching to/from alternate screen. Most do not...
By the way (same issue of some/most), if a terminal implements the original xterm 47 code alternate-screen switching, it is possible to switch back into the alternate screen without clearing it. I've noticed some which set TERM=xterm which do not implement this (only implementing the later 1049 code) - ymmv
You can see how the 47 code is used in a normal terminal description by looking at the smcup and rmcup capabilities from
infocmp xterm-old
which shows these items (among others):
rmcup=E[2JE[?47lE8,
smcup=E7E[?47h,
The E[2J in rmcup clears the (alternate) screen before switching back to the normal screen. The E7 and E8 save/restore the cursor position (for the normal screen). If you really wanted to, you could replace those capabilities with whatever xterm-compatible terminal description, omitting the clear-screen part, allowing you to do
tput smcup
tput rmcup
from the command-line and see what was on the alternate screen. It wouldn't be nice (since your command-line would overwrite parts of it), but it might help.
It's not needed in xterm, since xterm has a menu option for switching back/forth. But you might find that approach useful.
Further reading:
Why doesn't the screen clear when running vi? (xterm FAQ)- XTerm Control Sequences
answered 2 hours ago
Thomas Dickey
51.1k593162
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Some terminals (such as xterm) have a menu setting which enable/disables switching to/from alternate screen. Most do not...
By the way (same issue of some/most), if a terminal implements the original xterm 47 code alternate-screen switching, it is possible to switch back into the alternate screen without clearing it. I've noticed some which set TERM=xterm which do not implement this (only implementing the later 1049 code) - ymmv
You can see how the 47 code is used in a normal terminal description by looking at the smcup and rmcup capabilities from
infocmp xterm-old
which shows these items (among others):
rmcup=E[2JE[?47lE8,
smcup=E7E[?47h,
The E[2J in rmcup clears the (alternate) screen before switching back to the normal screen. The E7 and E8 save/restore the cursor position (for the normal screen). If you really wanted to, you could replace those capabilities with whatever xterm-compatible terminal description, omitting the clear-screen part, allowing you to do
tput smcup
tput rmcup
from the command-line and see what was on the alternate screen. It wouldn't be nice (since your command-line would overwrite parts of it), but it might help.
It's not needed in xterm, since xterm has a menu option for switching back/forth. But you might find that approach useful.
Further reading:
Why doesn't the screen clear when running vi? (xterm FAQ)- XTerm Control Sequences
answered 2 hours ago
Thomas Dickey
51.1k593162
Some terminals (such as xterm) have a menu setting which enable/disables switching to/from alternate screen. Most do not...
By the way (same issue of some/most), if a terminal implements the original xterm 47 code alternate-screen switching, it is possible to switch back into the alternate screen without clearing it. I've noticed some which set TERM=xterm which do not implement this (only implementing the later 1049 code) - ymmv
You can see how the 47 code is used in a normal terminal description by looking at the smcup and rmcup capabilities from
infocmp xterm-old
which shows these items (among others):
rmcup=E[2JE[?47lE8,
smcup=E7E[?47h,
The E[2J in rmcup clears the (alternate) screen before switching back to the normal screen. The E7 and E8 save/restore the cursor position (for the normal screen). If you really wanted to, you could replace those capabilities with whatever xterm-compatible terminal description, omitting the clear-screen part, allowing you to do
tput smcup
tput rmcup
from the command-line and see what was on the alternate screen. It wouldn't be nice (since your command-line would overwrite parts of it), but it might help.
It's not needed in xterm, since xterm has a menu option for switching back/forth. But you might find that approach useful.
Further reading:
Why doesn't the screen clear when running vi? (xterm FAQ)- XTerm Control Sequences
answered 2 hours ago
Thomas Dickey
51.1k593162
answered 2 hours ago
Thomas Dickey
51.1k593162
answered 2 hours ago
Thomas Dickey
51.1k593162
answered 2 hours ago
Thomas Dickey
51.1k593162
51.1k593162
add a comment |Â
add a comment |Â
up vote
2
down vote
use | . cat.
Stepwise: press |, then at the |mark: prompt press ., then at the ! prompt enter cat, then at the |done (press RETURN) prompt press Enter again; when you quit less, the current page we be left on the screen.
If you want the output to be processed as it was by less (with backspace+underscore transformed to underline, non-printable characters shown as <XX>, etc), use less -FX instead of cat.
from the less(1) manpage:
| <m> shell-command
<m> represents any mark letter. Pipes a section of the input
file to the given shell command. The section of the file to be
piped is between the first line on the current screen and the
position marked by the letter. <m> may also be ^ or $ to indi-
cate beginning or end of file respectively. If <m> is . or new-
line, the current screen is piped.
Afterwards, if you want to simply zap the rmcup/smcup alternate screen switching without having to reconfigure again and again every xterm clone, you can use this command:
infocmp | sed 's/[sr]mcup=[^=]*,//g' | tic -
This will write inside ~/.terminfo a terminal description for your current terminal with the codes for alternate screen switching omitted. It should be used in preference to that from /usr/share/terminfo by most programs.
edited 13 mins ago
Jeff Schaller
34.5k951115
answered 2 hours ago
qubert
1934
That prints the file which less is rendering, but it's not the same, e.g., if it contains non-printing characters (and does not affect the reset).
– Thomas Dickey
2 hours ago
@ThomasDickey I hope I addressed your objections in the last revision.
– qubert
2 hours ago
That's better (writing an approximation to the normal screen), though as noted, you can't modify the reset from within less :-)
– Thomas Dickey
2 hours ago
This is ingenious. To make sure I understand what's happening, less writes to the alternate screen and the shell out to cat writes to the normal screen?
– William Pursell
1 hour ago
@WilliamPursell exactly.
– qubert
1 hour ago
add a comment |Â
up vote
2
down vote
use | . cat.
Stepwise: press |, then at the |mark: prompt press ., then at the ! prompt enter cat, then at the |done (press RETURN) prompt press Enter again; when you quit less, the current page we be left on the screen.
If you want the output to be processed as it was by less (with backspace+underscore transformed to underline, non-printable characters shown as <XX>, etc), use less -FX instead of cat.
from the less(1) manpage:
| <m> shell-command
<m> represents any mark letter. Pipes a section of the input
file to the given shell command. The section of the file to be
piped is between the first line on the current screen and the
position marked by the letter. <m> may also be ^ or $ to indi-
cate beginning or end of file respectively. If <m> is . or new-
line, the current screen is piped.
Afterwards, if you want to simply zap the rmcup/smcup alternate screen switching without having to reconfigure again and again every xterm clone, you can use this command:
infocmp | sed 's/[sr]mcup=[^=]*,//g' | tic -
This will write inside ~/.terminfo a terminal description for your current terminal with the codes for alternate screen switching omitted. It should be used in preference to that from /usr/share/terminfo by most programs.
edited 13 mins ago
Jeff Schaller
34.5k951115
answered 2 hours ago
qubert
1934
That prints the file which less is rendering, but it's not the same, e.g., if it contains non-printing characters (and does not affect the reset).
– Thomas Dickey
2 hours ago
@ThomasDickey I hope I addressed your objections in the last revision.
– qubert
2 hours ago
That's better (writing an approximation to the normal screen), though as noted, you can't modify the reset from within less :-)
– Thomas Dickey
2 hours ago
This is ingenious. To make sure I understand what's happening, less writes to the alternate screen and the shell out to cat writes to the normal screen?
– William Pursell
1 hour ago
@WilliamPursell exactly.
– qubert
1 hour ago
add a comment |Â
up vote
2
down vote
up vote
2
down vote
use | . cat.
Stepwise: press |, then at the |mark: prompt press ., then at the ! prompt enter cat, then at the |done (press RETURN) prompt press Enter again; when you quit less, the current page we be left on the screen.
If you want the output to be processed as it was by less (with backspace+underscore transformed to underline, non-printable characters shown as <XX>, etc), use less -FX instead of cat.
from the less(1) manpage:
| <m> shell-command
<m> represents any mark letter. Pipes a section of the input
file to the given shell command. The section of the file to be
piped is between the first line on the current screen and the
position marked by the letter. <m> may also be ^ or $ to indi-
cate beginning or end of file respectively. If <m> is . or new-
line, the current screen is piped.
Afterwards, if you want to simply zap the rmcup/smcup alternate screen switching without having to reconfigure again and again every xterm clone, you can use this command:
infocmp | sed 's/[sr]mcup=[^=]*,//g' | tic -
This will write inside ~/.terminfo a terminal description for your current terminal with the codes for alternate screen switching omitted. It should be used in preference to that from /usr/share/terminfo by most programs.
edited 13 mins ago
Jeff Schaller
34.5k951115
answered 2 hours ago
qubert
1934
use | . cat.
Stepwise: press |, then at the |mark: prompt press ., then at the ! prompt enter cat, then at the |done (press RETURN) prompt press Enter again; when you quit less, the current page we be left on the screen.
If you want the output to be processed as it was by less (with backspace+underscore transformed to underline, non-printable characters shown as <XX>, etc), use less -FX instead of cat.
from the less(1) manpage:
| <m> shell-command
<m> represents any mark letter. Pipes a section of the input
file to the given shell command. The section of the file to be
piped is between the first line on the current screen and the
position marked by the letter. <m> may also be ^ or $ to indi-
cate beginning or end of file respectively. If <m> is . or new-
line, the current screen is piped.
Afterwards, if you want to simply zap the rmcup/smcup alternate screen switching without having to reconfigure again and again every xterm clone, you can use this command:
infocmp | sed 's/[sr]mcup=[^=]*,//g' | tic -
This will write inside ~/.terminfo a terminal description for your current terminal with the codes for alternate screen switching omitted. It should be used in preference to that from /usr/share/terminfo by most programs.
edited 13 mins ago
Jeff Schaller
34.5k951115
answered 2 hours ago
qubert
1934
edited 13 mins ago
Jeff Schaller
34.5k951115
edited 13 mins ago
Jeff Schaller
34.5k951115
edited 13 mins ago
Jeff Schaller
34.5k951115
34.5k951115
answered 2 hours ago
qubert
1934
answered 2 hours ago
qubert
1934
answered 2 hours ago
qubert
1934
1934
That prints the file which less is rendering, but it's not the same, e.g., if it contains non-printing characters (and does not affect the reset).
– Thomas Dickey
2 hours ago
@ThomasDickey I hope I addressed your objections in the last revision.
– qubert
2 hours ago
That's better (writing an approximation to the normal screen), though as noted, you can't modify the reset from within less :-)
– Thomas Dickey
2 hours ago
This is ingenious. To make sure I understand what's happening, less writes to the alternate screen and the shell out to cat writes to the normal screen?
– William Pursell
1 hour ago
@WilliamPursell exactly.
– qubert
1 hour ago
add a comment |Â
That prints the file which less is rendering, but it's not the same, e.g., if it contains non-printing characters (and does not affect the reset).
– Thomas Dickey
2 hours ago
@ThomasDickey I hope I addressed your objections in the last revision.
– qubert
2 hours ago
That's better (writing an approximation to the normal screen), though as noted, you can't modify the reset from within less :-)
– Thomas Dickey
2 hours ago
This is ingenious. To make sure I understand what's happening, less writes to the alternate screen and the shell out to cat writes to the normal screen?
– William Pursell
1 hour ago
@WilliamPursell exactly.
– qubert
1 hour ago
That prints the file which less is rendering, but it's not the same, e.g., if it contains non-printing characters (and does not affect the reset).
– Thomas Dickey
2 hours ago
That prints the file which less is rendering, but it's not the same, e.g., if it contains non-printing characters (and does not affect the reset).
– Thomas Dickey
2 hours ago
@ThomasDickey I hope I addressed your objections in the last revision.
– qubert
2 hours ago
@ThomasDickey I hope I addressed your objections in the last revision.
– qubert
2 hours ago
That's better (writing an approximation to the normal screen), though as noted, you can't modify the reset from within less :-)
– Thomas Dickey
2 hours ago
That's better (writing an approximation to the normal screen), though as noted, you can't modify the reset from within less :-)
– Thomas Dickey
2 hours ago
This is ingenious. To make sure I understand what's happening, less writes to the alternate screen and the shell out to cat writes to the normal screen?
– William Pursell
1 hour ago
This is ingenious. To make sure I understand what's happening, less writes to the alternate screen and the shell out to cat writes to the normal screen?
– William Pursell
1 hour ago
@WilliamPursell exactly.
– qubert
1 hour ago
@WilliamPursell exactly.
– qubert
1 hour ago
add a comment |Â
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short - no. long - see my answer.
– Thomas Dickey
2 hours ago