Change the shape that shows a for loop
I have the following code:
#!/bin/bash
FSTAB=` grep -vE "^#|swap|UUID" /etc/fstab | awk '{print $1,$2,$3}'`
for i in $FSTAB
do
echo "$i"
done
return this:
/dev/mapper/centos-root
/
xfs
/dev/sdb2
/hdos
xfs
The problem is that later I want to compare it, so I am returning it with line breaks and I want it to be returned in a single line without jumps, that is to say:
/dev/mapper/centos-root / xfs
/dev/sdb2 /hdos xfs
bash shell-script shell scripting
asked Jan 30 at 21:17
ortigaortiga
83
|
show 5 more comments
I have the following code:
#!/bin/bash
FSTAB=` grep -vE "^#|swap|UUID" /etc/fstab | awk '{print $1,$2,$3}'`
for i in $FSTAB
do
echo "$i"
done
return this:
/dev/mapper/centos-root
/
xfs
/dev/sdb2
/hdos
xfs
The problem is that later I want to compare it, so I am returning it with line breaks and I want it to be returned in a single line without jumps, that is to say:
/dev/mapper/centos-root / xfs
/dev/sdb2 /hdos xfs
bash shell-script shell scripting
asked Jan 30 at 21:17
ortigaortiga
83
for [...]; done | tr -d 'n'.
– DopeGhoti
Jan 30 at 21:23
You'd better let us know what you are compare it to later (or even better, what the overall issue is that you're trying to solve). It may not be needed to output anything at all. In fact, the safest way to store the pathnames for later use would be in an array. That would enable you to handle pathnames with whitespaces and other funky names.
– Kusalananda
Jan 30 at 21:26
1
Orawk '$0 ! ~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab.
– DopeGhoti
Jan 30 at 21:33
1
Or lettingawkwrite to stdout (:
– DopeGhoti
Jan 30 at 21:34
1
My life got a lot easier (and involved a lot fewer pipe fittings) the day I realized thatgrepping intoawkis a kissing cousin to the Useless Use of Cat.
– DopeGhoti
Jan 30 at 21:42
|
show 5 more comments
I have the following code:
#!/bin/bash
FSTAB=` grep -vE "^#|swap|UUID" /etc/fstab | awk '{print $1,$2,$3}'`
for i in $FSTAB
do
echo "$i"
done
return this:
/dev/mapper/centos-root
/
xfs
/dev/sdb2
/hdos
xfs
The problem is that later I want to compare it, so I am returning it with line breaks and I want it to be returned in a single line without jumps, that is to say:
/dev/mapper/centos-root / xfs
/dev/sdb2 /hdos xfs
bash shell-script shell scripting
asked Jan 30 at 21:17
ortigaortiga
83
I have the following code:
#!/bin/bash
FSTAB=` grep -vE "^#|swap|UUID" /etc/fstab | awk '{print $1,$2,$3}'`
for i in $FSTAB
do
echo "$i"
done
return this:
/dev/mapper/centos-root
/
xfs
/dev/sdb2
/hdos
xfs
The problem is that later I want to compare it, so I am returning it with line breaks and I want it to be returned in a single line without jumps, that is to say:
/dev/mapper/centos-root / xfs
/dev/sdb2 /hdos xfs
bash shell-script shell scripting
bash shell-script shell scripting
asked Jan 30 at 21:17
ortigaortiga
83
asked Jan 30 at 21:17
ortigaortiga
83
edited Jan 30 at 21:51
ortiga
asked Jan 30 at 21:17
ortigaortiga
83
asked Jan 30 at 21:17
ortigaortiga
83
asked Jan 30 at 21:17
ortigaortiga
83
83
for [...]; done | tr -d 'n'.
– DopeGhoti
Jan 30 at 21:23
You'd better let us know what you are compare it to later (or even better, what the overall issue is that you're trying to solve). It may not be needed to output anything at all. In fact, the safest way to store the pathnames for later use would be in an array. That would enable you to handle pathnames with whitespaces and other funky names.
– Kusalananda
Jan 30 at 21:26
1
Orawk '$0 ! ~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab.
– DopeGhoti
Jan 30 at 21:33
1
Or lettingawkwrite to stdout (:
– DopeGhoti
Jan 30 at 21:34
1
My life got a lot easier (and involved a lot fewer pipe fittings) the day I realized thatgrepping intoawkis a kissing cousin to the Useless Use of Cat.
– DopeGhoti
Jan 30 at 21:42
|
show 5 more comments
for [...]; done | tr -d 'n'.
– DopeGhoti
Jan 30 at 21:23
You'd better let us know what you are compare it to later (or even better, what the overall issue is that you're trying to solve). It may not be needed to output anything at all. In fact, the safest way to store the pathnames for later use would be in an array. That would enable you to handle pathnames with whitespaces and other funky names.
– Kusalananda
Jan 30 at 21:26
1
Orawk '$0 ! ~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab.
– DopeGhoti
Jan 30 at 21:33
1
Or lettingawkwrite to stdout (:
– DopeGhoti
Jan 30 at 21:34
1
My life got a lot easier (and involved a lot fewer pipe fittings) the day I realized thatgrepping intoawkis a kissing cousin to the Useless Use of Cat.
– DopeGhoti
Jan 30 at 21:42
for [...]; done | tr -d 'n'.– DopeGhoti
Jan 30 at 21:23
for [...]; done | tr -d 'n'.– DopeGhoti
Jan 30 at 21:23
You'd better let us know what you are compare it to later (or even better, what the overall issue is that you're trying to solve). It may not be needed to output anything at all. In fact, the safest way to store the pathnames for later use would be in an array. That would enable you to handle pathnames with whitespaces and other funky names.
– Kusalananda
Jan 30 at 21:26
You'd better let us know what you are compare it to later (or even better, what the overall issue is that you're trying to solve). It may not be needed to output anything at all. In fact, the safest way to store the pathnames for later use would be in an array. That would enable you to handle pathnames with whitespaces and other funky names.
– Kusalananda
Jan 30 at 21:26
1
1
Or
awk '$0 ! ~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab.– DopeGhoti
Jan 30 at 21:33
Or
awk '$0 ! ~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab.– DopeGhoti
Jan 30 at 21:33
1
1
Or letting
awk write to stdout (:– DopeGhoti
Jan 30 at 21:34
Or letting
awk write to stdout (:– DopeGhoti
Jan 30 at 21:34
1
1
My life got a lot easier (and involved a lot fewer pipe fittings) the day I realized that
grepping into awk is a kissing cousin to the Useless Use of Cat.– DopeGhoti
Jan 30 at 21:42
My life got a lot easier (and involved a lot fewer pipe fittings) the day I realized that
grepping into awk is a kissing cousin to the Useless Use of Cat.– DopeGhoti
Jan 30 at 21:42
|
show 5 more comments
3 Answers
3
active
oldest
votes
Regardless of how you fill the FSTAB variable, the unquoted expansion of it in the for loop removes the distinction between different kinds of white space. (See: When is double-quoting necessary? and Why does my shell script choke on whitespace or other special characters?)
To work around that, either set IFS to split only on newlines, or loop over the lines with a while read loop:
$ fstab=$(grep /etc/fstab ...)
$ while IFS= read -r line; do
printf "$linen"
done <<< "$fstab"
You could also use while read -r dev mnt fs; do ... if you wanted the fields in separate variables.
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
add a comment |
Your entire variable assignment command chain there can be done in one awk rather than piping grep's output into awk:
FSTAB=` grep -v "^#" /etc/fstab | grep . | grep -v "swap" | grep -v "UUID" | awk '{print $1,$2,$3}'`
can instead be
FSTAB="$(awk 'NF && $0 !~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab)"
Newlines will be embedded in the variable, so you don't need to loop anything, you can simply echo "$FSTAB".
However, rather than parsing /etc/fstab into a variable and then parsing that, it would probably be better to parse /etc/fstab directly with a more involved awk script that does exactly what you need to with the output you're currently scraping from it.
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
add a comment |
Just GNU egrep:
egrep -v "^#|swap|UUID" /etc/fstab | egrep -o '^(S*s*){1,3}'
answered Feb 4 at 4:32
agcagc
4,67111137
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
Regardless of how you fill the FSTAB variable, the unquoted expansion of it in the for loop removes the distinction between different kinds of white space. (See: When is double-quoting necessary? and Why does my shell script choke on whitespace or other special characters?)
To work around that, either set IFS to split only on newlines, or loop over the lines with a while read loop:
$ fstab=$(grep /etc/fstab ...)
$ while IFS= read -r line; do
printf "$linen"
done <<< "$fstab"
You could also use while read -r dev mnt fs; do ... if you wanted the fields in separate variables.
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
add a comment |
Regardless of how you fill the FSTAB variable, the unquoted expansion of it in the for loop removes the distinction between different kinds of white space. (See: When is double-quoting necessary? and Why does my shell script choke on whitespace or other special characters?)
To work around that, either set IFS to split only on newlines, or loop over the lines with a while read loop:
$ fstab=$(grep /etc/fstab ...)
$ while IFS= read -r line; do
printf "$linen"
done <<< "$fstab"
You could also use while read -r dev mnt fs; do ... if you wanted the fields in separate variables.
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
add a comment |
Regardless of how you fill the FSTAB variable, the unquoted expansion of it in the for loop removes the distinction between different kinds of white space. (See: When is double-quoting necessary? and Why does my shell script choke on whitespace or other special characters?)
To work around that, either set IFS to split only on newlines, or loop over the lines with a while read loop:
$ fstab=$(grep /etc/fstab ...)
$ while IFS= read -r line; do
printf "$linen"
done <<< "$fstab"
You could also use while read -r dev mnt fs; do ... if you wanted the fields in separate variables.
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
Regardless of how you fill the FSTAB variable, the unquoted expansion of it in the for loop removes the distinction between different kinds of white space. (See: When is double-quoting necessary? and Why does my shell script choke on whitespace or other special characters?)
To work around that, either set IFS to split only on newlines, or loop over the lines with a while read loop:
$ fstab=$(grep /etc/fstab ...)
$ while IFS= read -r line; do
printf "$linen"
done <<< "$fstab"
You could also use while read -r dev mnt fs; do ... if you wanted the fields in separate variables.
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
answered Jan 30 at 22:06
ilkkachuilkkachu
58.3k890164
58.3k890164
add a comment |
add a comment |
Your entire variable assignment command chain there can be done in one awk rather than piping grep's output into awk:
FSTAB=` grep -v "^#" /etc/fstab | grep . | grep -v "swap" | grep -v "UUID" | awk '{print $1,$2,$3}'`
can instead be
FSTAB="$(awk 'NF && $0 !~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab)"
Newlines will be embedded in the variable, so you don't need to loop anything, you can simply echo "$FSTAB".
However, rather than parsing /etc/fstab into a variable and then parsing that, it would probably be better to parse /etc/fstab directly with a more involved awk script that does exactly what you need to with the output you're currently scraping from it.
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
add a comment |
Your entire variable assignment command chain there can be done in one awk rather than piping grep's output into awk:
FSTAB=` grep -v "^#" /etc/fstab | grep . | grep -v "swap" | grep -v "UUID" | awk '{print $1,$2,$3}'`
can instead be
FSTAB="$(awk 'NF && $0 !~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab)"
Newlines will be embedded in the variable, so you don't need to loop anything, you can simply echo "$FSTAB".
However, rather than parsing /etc/fstab into a variable and then parsing that, it would probably be better to parse /etc/fstab directly with a more involved awk script that does exactly what you need to with the output you're currently scraping from it.
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
add a comment |
Your entire variable assignment command chain there can be done in one awk rather than piping grep's output into awk:
FSTAB=` grep -v "^#" /etc/fstab | grep . | grep -v "swap" | grep -v "UUID" | awk '{print $1,$2,$3}'`
can instead be
FSTAB="$(awk 'NF && $0 !~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab)"
Newlines will be embedded in the variable, so you don't need to loop anything, you can simply echo "$FSTAB".
However, rather than parsing /etc/fstab into a variable and then parsing that, it would probably be better to parse /etc/fstab directly with a more involved awk script that does exactly what you need to with the output you're currently scraping from it.
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
Your entire variable assignment command chain there can be done in one awk rather than piping grep's output into awk:
FSTAB=` grep -v "^#" /etc/fstab | grep . | grep -v "swap" | grep -v "UUID" | awk '{print $1,$2,$3}'`
can instead be
FSTAB="$(awk 'NF && $0 !~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab)"
Newlines will be embedded in the variable, so you don't need to loop anything, you can simply echo "$FSTAB".
However, rather than parsing /etc/fstab into a variable and then parsing that, it would probably be better to parse /etc/fstab directly with a more involved awk script that does exactly what you need to with the output you're currently scraping from it.
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
edited Jan 30 at 22:17
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
answered Jan 30 at 21:40
DopeGhotiDopeGhoti
45.4k55988
45.4k55988
add a comment |
add a comment |
Just GNU egrep:
egrep -v "^#|swap|UUID" /etc/fstab | egrep -o '^(S*s*){1,3}'
answered Feb 4 at 4:32
agcagc
4,67111137
add a comment |
Just GNU egrep:
egrep -v "^#|swap|UUID" /etc/fstab | egrep -o '^(S*s*){1,3}'
answered Feb 4 at 4:32
agcagc
4,67111137
add a comment |
Just GNU egrep:
egrep -v "^#|swap|UUID" /etc/fstab | egrep -o '^(S*s*){1,3}'
answered Feb 4 at 4:32
agcagc
4,67111137
Just GNU egrep:
egrep -v "^#|swap|UUID" /etc/fstab | egrep -o '^(S*s*){1,3}'
answered Feb 4 at 4:32
agcagc
4,67111137
answered Feb 4 at 4:32
agcagc
4,67111137
answered Feb 4 at 4:32
agcagc
4,67111137
answered Feb 4 at 4:32
agcagc
4,67111137
4,67111137
add a comment |
add a comment |
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for [...]; done | tr -d 'n'.– DopeGhoti
Jan 30 at 21:23
You'd better let us know what you are compare it to later (or even better, what the overall issue is that you're trying to solve). It may not be needed to output anything at all. In fact, the safest way to store the pathnames for later use would be in an array. That would enable you to handle pathnames with whitespaces and other funky names.
– Kusalananda
Jan 30 at 21:26
1
Or
awk '$0 ! ~ /^#|swap|UUID/ {print $1, $2, $3}' /etc/fstab.– DopeGhoti
Jan 30 at 21:33
1
Or letting
awkwrite to stdout (:– DopeGhoti
Jan 30 at 21:34
1
My life got a lot easier (and involved a lot fewer pipe fittings) the day I realized that
grepping intoawkis a kissing cousin to the Useless Use of Cat.– DopeGhoti
Jan 30 at 21:42