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why do I have to pipe perl output into a new perl command
Pipe output and capture exit status in BashHow do I set a variable to the output of a command in Bash?Why does modern Perl avoid UTF-8 by default?Setting an environment variable before a command in bash not working for second command in a pipeSome GNUPlot terminals work from command line, but not when called from Perl (piping)Parsing command output from bashSpecific pipe command in Ubuntu's shell handling in CMulti-line, double quoted string triggers history expansion on subsequent single-quoted commands it gets piped toPerl module File:Slurp with STDIN pipedPerl command works on command line but not within a bash script
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I want to remove whitespace between back-tick (x60) and word characters, inside of a perl script that performs many other regex substitutions. If I print the result of the earlier substitutions to the bash shell and then pipe into a new perl invocation, it works. But inside a single perl invocation, it doesn't. In the example below, the third line (a single perl command) does not work whereas the fourth line (two separate commands) does work.
printf '%b' 'Well, `n he said it n'
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' | perl -p -e 'use strict; use warnings; s|([x60])s*(w)|$1$2|g;'; echo
Why does it not work inside a single perl invocation? I thought we were supposed to avoid multiple or nested pipes (subshells).
This is perl 5, version 18 and GNU bash, version 3.2.57(1) in BSD unix.
bash perl recursion pipe string-substitution
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
add a comment |
I want to remove whitespace between back-tick (x60) and word characters, inside of a perl script that performs many other regex substitutions. If I print the result of the earlier substitutions to the bash shell and then pipe into a new perl invocation, it works. But inside a single perl invocation, it doesn't. In the example below, the third line (a single perl command) does not work whereas the fourth line (two separate commands) does work.
printf '%b' 'Well, `n he said it n'
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' | perl -p -e 'use strict; use warnings; s|([x60])s*(w)|$1$2|g;'; echo
Why does it not work inside a single perl invocation? I thought we were supposed to avoid multiple or nested pipes (subshells).
This is perl 5, version 18 and GNU bash, version 3.2.57(1) in BSD unix.
bash perl recursion pipe string-substitution
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
add a comment |
I want to remove whitespace between back-tick (x60) and word characters, inside of a perl script that performs many other regex substitutions. If I print the result of the earlier substitutions to the bash shell and then pipe into a new perl invocation, it works. But inside a single perl invocation, it doesn't. In the example below, the third line (a single perl command) does not work whereas the fourth line (two separate commands) does work.
printf '%b' 'Well, `n he said it n'
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' | perl -p -e 'use strict; use warnings; s|([x60])s*(w)|$1$2|g;'; echo
Why does it not work inside a single perl invocation? I thought we were supposed to avoid multiple or nested pipes (subshells).
This is perl 5, version 18 and GNU bash, version 3.2.57(1) in BSD unix.
bash perl recursion pipe string-substitution
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
I want to remove whitespace between back-tick (x60) and word characters, inside of a perl script that performs many other regex substitutions. If I print the result of the earlier substitutions to the bash shell and then pipe into a new perl invocation, it works. But inside a single perl invocation, it doesn't. In the example below, the third line (a single perl command) does not work whereas the fourth line (two separate commands) does work.
printf '%b' 'Well, `n he said it n'
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
printf '%b' 'Well, `n he said it n' | perl -p -e 'use strict; use warnings; s|n||g;' | perl -p -e 'use strict; use warnings; s|([x60])s*(w)|$1$2|g;'; echo
Why does it not work inside a single perl invocation? I thought we were supposed to avoid multiple or nested pipes (subshells).
This is perl 5, version 18 and GNU bash, version 3.2.57(1) in BSD unix.
bash perl recursion pipe string-substitution
bash perl recursion pipe string-substitution
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
asked Mar 26 at 22:34
Jacob WegelinJacob Wegelin
1531 silver badge6 bronze badges
1531 silver badge6 bronze badges
add a comment |
add a comment |
1 Answer
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Because your perl -p is splitting on newlines, your first perl removes them, and the second one sees everything as if it were on one line.
printf '%b' 'Well, `n he said it n' | perl -p0 -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
By telling perl to slurp it all in at once, the first s can remove the new lines, and the second will remove the spaces after your quote.
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
-0doesn't actually enable slurp mode; use-0777for that.
– ikegami
Mar 26 at 23:53
@Tanktalus, this is very helpful. Where are -0 and -0777 documented? How does syntax change to perform this in a perl script, rather than a command-line invocation?
– Jacob Wegelin
Mar 27 at 1:52
@JacobWegelin see perldoc.perl.org/perlrun.html
– Shawn
Mar 27 at 2:08
add a comment |
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Because your perl -p is splitting on newlines, your first perl removes them, and the second one sees everything as if it were on one line.
printf '%b' 'Well, `n he said it n' | perl -p0 -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
By telling perl to slurp it all in at once, the first s can remove the new lines, and the second will remove the spaces after your quote.
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
-0doesn't actually enable slurp mode; use-0777for that.
– ikegami
Mar 26 at 23:53
@Tanktalus, this is very helpful. Where are -0 and -0777 documented? How does syntax change to perform this in a perl script, rather than a command-line invocation?
– Jacob Wegelin
Mar 27 at 1:52
@JacobWegelin see perldoc.perl.org/perlrun.html
– Shawn
Mar 27 at 2:08
add a comment |
Because your perl -p is splitting on newlines, your first perl removes them, and the second one sees everything as if it were on one line.
printf '%b' 'Well, `n he said it n' | perl -p0 -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
By telling perl to slurp it all in at once, the first s can remove the new lines, and the second will remove the spaces after your quote.
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
-0doesn't actually enable slurp mode; use-0777for that.
– ikegami
Mar 26 at 23:53
@Tanktalus, this is very helpful. Where are -0 and -0777 documented? How does syntax change to perform this in a perl script, rather than a command-line invocation?
– Jacob Wegelin
Mar 27 at 1:52
@JacobWegelin see perldoc.perl.org/perlrun.html
– Shawn
Mar 27 at 2:08
add a comment |
Because your perl -p is splitting on newlines, your first perl removes them, and the second one sees everything as if it were on one line.
printf '%b' 'Well, `n he said it n' | perl -p0 -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
By telling perl to slurp it all in at once, the first s can remove the new lines, and the second will remove the spaces after your quote.
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
Because your perl -p is splitting on newlines, your first perl removes them, and the second one sees everything as if it were on one line.
printf '%b' 'Well, `n he said it n' | perl -p0 -e 'use strict; use warnings; s|n||g; s|([x60])s*(w)|$1$2|g;' ; echo
By telling perl to slurp it all in at once, the first s can remove the new lines, and the second will remove the spaces after your quote.
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
answered Mar 26 at 22:42
TanktalusTanktalus
17.8k4 gold badges34 silver badges63 bronze badges
17.8k4 gold badges34 silver badges63 bronze badges
-0doesn't actually enable slurp mode; use-0777for that.
– ikegami
Mar 26 at 23:53
@Tanktalus, this is very helpful. Where are -0 and -0777 documented? How does syntax change to perform this in a perl script, rather than a command-line invocation?
– Jacob Wegelin
Mar 27 at 1:52
@JacobWegelin see perldoc.perl.org/perlrun.html
– Shawn
Mar 27 at 2:08
add a comment |
-0doesn't actually enable slurp mode; use-0777for that.
– ikegami
Mar 26 at 23:53
@Tanktalus, this is very helpful. Where are -0 and -0777 documented? How does syntax change to perform this in a perl script, rather than a command-line invocation?
– Jacob Wegelin
Mar 27 at 1:52
@JacobWegelin see perldoc.perl.org/perlrun.html
– Shawn
Mar 27 at 2:08
-0 doesn't actually enable slurp mode; use -0777 for that.– ikegami
Mar 26 at 23:53
-0 doesn't actually enable slurp mode; use -0777 for that.– ikegami
Mar 26 at 23:53
@Tanktalus, this is very helpful. Where are -0 and -0777 documented? How does syntax change to perform this in a perl script, rather than a command-line invocation?
– Jacob Wegelin
Mar 27 at 1:52
@Tanktalus, this is very helpful. Where are -0 and -0777 documented? How does syntax change to perform this in a perl script, rather than a command-line invocation?
– Jacob Wegelin
Mar 27 at 1:52
@JacobWegelin see perldoc.perl.org/perlrun.html
– Shawn
Mar 27 at 2:08
@JacobWegelin see perldoc.perl.org/perlrun.html
– Shawn
Mar 27 at 2:08
add a comment |
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