Revisions to Sed - Help Matching with Multi-Line Match

deleted 15 characters in body

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edited May 10 at 17:49

41.6k
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[etc] in regex means any one of these characters, so it won't match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).

\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$\1\2
- captures any characters (except newline) afterThese are references to the parts of the input that were matched pattern.by the first two $.*$ patterns:
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

[etc] in regex means any one of these characters, so it won't match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).

\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$
- captures any characters (except newline) after the matched pattern.
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

[etc] in regex means any one of these characters, so it won't match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above.
$.*$
- captures any characters (except newline) before the matched pattern.
\1\2
- These are references to the parts of the input that were matched by the first two $.*$ patterns:
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

added 1 character in body

Source Link

edited May 10 at 14:39

terdon ♦

252.7k
69
481
719

[etc] in regex means any one of these characters, so it wontwon't match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).
\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$
- captures any characters (except newline) after the matched pattern.
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

[etc] in regex means any one of these characters, so it wont match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).
\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$
- captures any characters (except newline) after the matched pattern.
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

[etc] in regex means any one of these characters, so it won't match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).
\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$
- captures any characters (except newline) after the matched pattern.
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

added 1 character in body

Source Link

edited May 10 at 12:53

jesse_b

41.6k
14
109
163

[etc] in regex means any one of these characters, so it wont match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).
\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$
- captures any characters (except newline) after the matched pattern.
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -PzoqPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

[etc] in regex means any one of these characters, so it wont match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).
\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$
- captures any characters (except newline) after the matched pattern.
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -Pzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

[etc] in regex means any one of these characters, so it wont match a literal [etc].

with sed:

sed -zi '/\[etc\]\ntransient *= *true/!s|\(.*\)\(.*\)|\1\2[etc]\ntransient = true\n|' file

'/\[etc\]\ntransient *= *true/!
- checks whether the block [etc] followed by transient = true exists in the file.
transient *= *true
- Matches the string transient = true, with optional spaces around the = sign (* allows for zero or more spaces).
!
- This negates the match, so the subsequent replacement will only occur if the pattern is not found.
s|$.*$$.*$|\1\2[etc]\ntransient = true\n|
- The substitution part, which operates on the content that doesn’t match the pattern from above (![etc] block).
\1\2
- These are references to the parts of the input that were matched by the first two (.*) patterns:
$.*$
- captures any characters (except newline) before the matched pattern.
$.*$
- captures any characters (except newline) after the matched pattern.
[etc]\ntransient = true\n
- Will be inserted if the pattern is not found.

With grep/printf:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  printf '%s\n%s\n' "[etc]" "transient = true" >> file
fi

Or with grep/ed:

if ! grep -qPzo '\[etc\]\s*\n\s*transient\s*=\s*true' file; then
  ed -s file <<'EOF'
$a
[etc]
transient = true
.
w
q
EOF
fi

grep will check for the pattern and if it is not found ed will run:

-s
- tells ed to run in "silent" mode, suppressing most output.
$a
- appends text after the last line in the file.
.
- ed command to indicate the end of the text input.
w
- write the changes to the file.
q
- quit

Source Link

answered May 10 at 12:40

jesse_b

41.6k
14
109
163

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