How to filter a string against the characters from a variable?
up vote
2
down vote
favorite
1
I am trying to remove special characters (by passing them as a variable) from a string variable below command able to remove single characters not multiple?
string=#@$AAA%*
a=#$@%* # Special characters which have to remove from variable
b=`echo $string|sed 's/${a}//g'`
echo $b
bash variable string
edited Dec 4 at 12:07
αғsнιη
16.5k102765
asked Dec 4 at 9:52
Harish a
233
add a comment |
up vote
2
down vote
favorite
1
I am trying to remove special characters (by passing them as a variable) from a string variable below command able to remove single characters not multiple?
string=#@$AAA%*
a=#$@%* # Special characters which have to remove from variable
b=`echo $string|sed 's/${a}//g'`
echo $b
bash variable string
edited Dec 4 at 12:07
αғsнιη
16.5k102765
asked Dec 4 at 9:52
Harish a
233
please also keep in mind to quote your variable that you should. read Why does my shell script choke on whitespace or other special characters?.
– αғsнιη
Dec 4 at 12:17
add a comment |
up vote
2
down vote
favorite
1
up vote
2
down vote
favorite
1
1
I am trying to remove special characters (by passing them as a variable) from a string variable below command able to remove single characters not multiple?
string=#@$AAA%*
a=#$@%* # Special characters which have to remove from variable
b=`echo $string|sed 's/${a}//g'`
echo $b
bash variable string
edited Dec 4 at 12:07
αғsнιη
16.5k102765
asked Dec 4 at 9:52
Harish a
233
I am trying to remove special characters (by passing them as a variable) from a string variable below command able to remove single characters not multiple?
string=#@$AAA%*
a=#$@%* # Special characters which have to remove from variable
b=`echo $string|sed 's/${a}//g'`
echo $b
bash variable string
bash variable string
edited Dec 4 at 12:07
αғsнιη
16.5k102765
asked Dec 4 at 9:52
Harish a
233
edited Dec 4 at 12:07
αғsнιη
16.5k102765
asked Dec 4 at 9:52
Harish a
233
edited Dec 4 at 12:07
αғsнιη
16.5k102765
edited Dec 4 at 12:07
αғsнιη
16.5k102765
edited Dec 4 at 12:07
αғsнιη
16.5k102765
16.5k102765
asked Dec 4 at 9:52
Harish a
233
asked Dec 4 at 9:52
Harish a
233
asked Dec 4 at 9:52
Harish a
233
233
please also keep in mind to quote your variable that you should. read Why does my shell script choke on whitespace or other special characters?.
– αғsнιη
Dec 4 at 12:17
add a comment |
please also keep in mind to quote your variable that you should. read Why does my shell script choke on whitespace or other special characters?.
– αғsнιη
Dec 4 at 12:17
please also keep in mind to quote your variable that you should. read Why does my shell script choke on whitespace or other special characters?.
– αғsнιη
Dec 4 at 12:17
please also keep in mind to quote your variable that you should. read Why does my shell script choke on whitespace or other special characters?.
– αғsнιη
Dec 4 at 12:17
add a comment |
2 Answers
2
active
oldest
votes
up vote
2
down vote
accepted
There are a few things wrong with your commands.
string=#@$AAA%*anda=#$@%*: here the$AAAand$@parts are interpreted as variables. You should single-quote the strings so that they are interpreted literally.- For the
sedpart, you are asking it to replace a literal string of#$@%*in order with nothing. If you want separate characters, you'd need to use a different format, e.g. the character class[#$@%*]. However, in this case, I'd just usetr -dinstead, which is much simpler. - Also,
$(…)is preferred over backticks. - I'd also use a here-string (
<<<) instead of an echo, just to save a few cycles. - I noticed that Kusalananda edited my answer to add
"quotes around variables. I deliberated over this too, but figured I wouldn't because it would be simpler, and not necessary for your specific question. However, I agree that this is the "right" way to do things. I've added"quotes around the other variables and the$(…)construct; in this case they are unnecessary, but also good practice.
Hence the final commands are
string='#@$AAA%*'
a='#$@%*'
b="$(<<<"$string" tr -d "$a")"
echo "$b"
answered Dec 4 at 10:05
Sparhawk
9,20863890
You should've left it at @Kusalananda's edit. The extra quotes you added are absolutely useless -- unlike those around"$a"and"$b", they make no difference, no matter the value ofstringanda. Example:s='/b * .? * * b/'; a='/*'; b=$(<<<$s tr -d "$a"); echo "$b"
– mosvy
Dec 6 at 0:47
@mosvy Yes, good point… I guess my thinking was that Kusalananda's were also not necessary in this case either. Admittedly$bmay well contain whitespace in another variant, but$aalmost certainly would not (at least not in a way that would break). I agree that my quotes are even more useless, but I figured I'd use them for "good practice", in a general sense… which was likely Kusalananda's thinking? I've edited the question to point this out anyway.
– Sparhawk
Dec 6 at 0:59
the quotes around"$a"and"$b"are not just "good practice" (ie cargo cult). Try my example without either of them and you will see that they really make a difference.
– mosvy
Dec 6 at 1:02
@mosvy Ah yes okay. I forgot to use bash instead of my normal zsh. Yes, the*causes problems. Hopefully my edit includes this interpretation.
– Sparhawk
Dec 6 at 1:08
add a comment |
up vote
6
down vote
No need to run external commands when using recent shells' "parameter expansion":
echo ${string//["$a"]}
AAA
answered Dec 4 at 11:28
RudiC
3,9541312
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
accepted
There are a few things wrong with your commands.
string=#@$AAA%*anda=#$@%*: here the$AAAand$@parts are interpreted as variables. You should single-quote the strings so that they are interpreted literally.- For the
sedpart, you are asking it to replace a literal string of#$@%*in order with nothing. If you want separate characters, you'd need to use a different format, e.g. the character class[#$@%*]. However, in this case, I'd just usetr -dinstead, which is much simpler. - Also,
$(…)is preferred over backticks. - I'd also use a here-string (
<<<) instead of an echo, just to save a few cycles. - I noticed that Kusalananda edited my answer to add
"quotes around variables. I deliberated over this too, but figured I wouldn't because it would be simpler, and not necessary for your specific question. However, I agree that this is the "right" way to do things. I've added"quotes around the other variables and the$(…)construct; in this case they are unnecessary, but also good practice.
Hence the final commands are
string='#@$AAA%*'
a='#$@%*'
b="$(<<<"$string" tr -d "$a")"
echo "$b"
answered Dec 4 at 10:05
Sparhawk
9,20863890
You should've left it at @Kusalananda's edit. The extra quotes you added are absolutely useless -- unlike those around"$a"and"$b", they make no difference, no matter the value ofstringanda. Example:s='/b * .? * * b/'; a='/*'; b=$(<<<$s tr -d "$a"); echo "$b"
– mosvy
Dec 6 at 0:47
@mosvy Yes, good point… I guess my thinking was that Kusalananda's were also not necessary in this case either. Admittedly$bmay well contain whitespace in another variant, but$aalmost certainly would not (at least not in a way that would break). I agree that my quotes are even more useless, but I figured I'd use them for "good practice", in a general sense… which was likely Kusalananda's thinking? I've edited the question to point this out anyway.
– Sparhawk
Dec 6 at 0:59
the quotes around"$a"and"$b"are not just "good practice" (ie cargo cult). Try my example without either of them and you will see that they really make a difference.
– mosvy
Dec 6 at 1:02
@mosvy Ah yes okay. I forgot to use bash instead of my normal zsh. Yes, the*causes problems. Hopefully my edit includes this interpretation.
– Sparhawk
Dec 6 at 1:08
add a comment |
up vote
2
down vote
accepted
There are a few things wrong with your commands.
string=#@$AAA%*anda=#$@%*: here the$AAAand$@parts are interpreted as variables. You should single-quote the strings so that they are interpreted literally.- For the
sedpart, you are asking it to replace a literal string of#$@%*in order with nothing. If you want separate characters, you'd need to use a different format, e.g. the character class[#$@%*]. However, in this case, I'd just usetr -dinstead, which is much simpler. - Also,
$(…)is preferred over backticks. - I'd also use a here-string (
<<<) instead of an echo, just to save a few cycles. - I noticed that Kusalananda edited my answer to add
"quotes around variables. I deliberated over this too, but figured I wouldn't because it would be simpler, and not necessary for your specific question. However, I agree that this is the "right" way to do things. I've added"quotes around the other variables and the$(…)construct; in this case they are unnecessary, but also good practice.
Hence the final commands are
string='#@$AAA%*'
a='#$@%*'
b="$(<<<"$string" tr -d "$a")"
echo "$b"
answered Dec 4 at 10:05
Sparhawk
9,20863890
You should've left it at @Kusalananda's edit. The extra quotes you added are absolutely useless -- unlike those around"$a"and"$b", they make no difference, no matter the value ofstringanda. Example:s='/b * .? * * b/'; a='/*'; b=$(<<<$s tr -d "$a"); echo "$b"
– mosvy
Dec 6 at 0:47
@mosvy Yes, good point… I guess my thinking was that Kusalananda's were also not necessary in this case either. Admittedly$bmay well contain whitespace in another variant, but$aalmost certainly would not (at least not in a way that would break). I agree that my quotes are even more useless, but I figured I'd use them for "good practice", in a general sense… which was likely Kusalananda's thinking? I've edited the question to point this out anyway.
– Sparhawk
Dec 6 at 0:59
the quotes around"$a"and"$b"are not just "good practice" (ie cargo cult). Try my example without either of them and you will see that they really make a difference.
– mosvy
Dec 6 at 1:02
@mosvy Ah yes okay. I forgot to use bash instead of my normal zsh. Yes, the*causes problems. Hopefully my edit includes this interpretation.
– Sparhawk
Dec 6 at 1:08
add a comment |
up vote
2
down vote
accepted
up vote
2
down vote
accepted
There are a few things wrong with your commands.
string=#@$AAA%*anda=#$@%*: here the$AAAand$@parts are interpreted as variables. You should single-quote the strings so that they are interpreted literally.- For the
sedpart, you are asking it to replace a literal string of#$@%*in order with nothing. If you want separate characters, you'd need to use a different format, e.g. the character class[#$@%*]. However, in this case, I'd just usetr -dinstead, which is much simpler. - Also,
$(…)is preferred over backticks. - I'd also use a here-string (
<<<) instead of an echo, just to save a few cycles. - I noticed that Kusalananda edited my answer to add
"quotes around variables. I deliberated over this too, but figured I wouldn't because it would be simpler, and not necessary for your specific question. However, I agree that this is the "right" way to do things. I've added"quotes around the other variables and the$(…)construct; in this case they are unnecessary, but also good practice.
Hence the final commands are
string='#@$AAA%*'
a='#$@%*'
b="$(<<<"$string" tr -d "$a")"
echo "$b"
answered Dec 4 at 10:05
Sparhawk
9,20863890
There are a few things wrong with your commands.
string=#@$AAA%*anda=#$@%*: here the$AAAand$@parts are interpreted as variables. You should single-quote the strings so that they are interpreted literally.- For the
sedpart, you are asking it to replace a literal string of#$@%*in order with nothing. If you want separate characters, you'd need to use a different format, e.g. the character class[#$@%*]. However, in this case, I'd just usetr -dinstead, which is much simpler. - Also,
$(…)is preferred over backticks. - I'd also use a here-string (
<<<) instead of an echo, just to save a few cycles. - I noticed that Kusalananda edited my answer to add
"quotes around variables. I deliberated over this too, but figured I wouldn't because it would be simpler, and not necessary for your specific question. However, I agree that this is the "right" way to do things. I've added"quotes around the other variables and the$(…)construct; in this case they are unnecessary, but also good practice.
Hence the final commands are
string='#@$AAA%*'
a='#$@%*'
b="$(<<<"$string" tr -d "$a")"
echo "$b"
answered Dec 4 at 10:05
Sparhawk
9,20863890
edited Dec 6 at 0:59
answered Dec 4 at 10:05
Sparhawk
9,20863890
answered Dec 4 at 10:05
Sparhawk
9,20863890
answered Dec 4 at 10:05
Sparhawk
9,20863890
9,20863890
You should've left it at @Kusalananda's edit. The extra quotes you added are absolutely useless -- unlike those around"$a"and"$b", they make no difference, no matter the value ofstringanda. Example:s='/b * .? * * b/'; a='/*'; b=$(<<<$s tr -d "$a"); echo "$b"
– mosvy
Dec 6 at 0:47
@mosvy Yes, good point… I guess my thinking was that Kusalananda's were also not necessary in this case either. Admittedly$bmay well contain whitespace in another variant, but$aalmost certainly would not (at least not in a way that would break). I agree that my quotes are even more useless, but I figured I'd use them for "good practice", in a general sense… which was likely Kusalananda's thinking? I've edited the question to point this out anyway.
– Sparhawk
Dec 6 at 0:59
the quotes around"$a"and"$b"are not just "good practice" (ie cargo cult). Try my example without either of them and you will see that they really make a difference.
– mosvy
Dec 6 at 1:02
@mosvy Ah yes okay. I forgot to use bash instead of my normal zsh. Yes, the*causes problems. Hopefully my edit includes this interpretation.
– Sparhawk
Dec 6 at 1:08
add a comment |
You should've left it at @Kusalananda's edit. The extra quotes you added are absolutely useless -- unlike those around"$a"and"$b", they make no difference, no matter the value ofstringanda. Example:s='/b * .? * * b/'; a='/*'; b=$(<<<$s tr -d "$a"); echo "$b"
– mosvy
Dec 6 at 0:47
@mosvy Yes, good point… I guess my thinking was that Kusalananda's were also not necessary in this case either. Admittedly$bmay well contain whitespace in another variant, but$aalmost certainly would not (at least not in a way that would break). I agree that my quotes are even more useless, but I figured I'd use them for "good practice", in a general sense… which was likely Kusalananda's thinking? I've edited the question to point this out anyway.
– Sparhawk
Dec 6 at 0:59
the quotes around"$a"and"$b"are not just "good practice" (ie cargo cult). Try my example without either of them and you will see that they really make a difference.
– mosvy
Dec 6 at 1:02
@mosvy Ah yes okay. I forgot to use bash instead of my normal zsh. Yes, the*causes problems. Hopefully my edit includes this interpretation.
– Sparhawk
Dec 6 at 1:08
You should've left it at @Kusalananda's edit. The extra quotes you added are absolutely useless -- unlike those around
"$a" and "$b", they make no difference, no matter the value of string and a. Example: s='/b * .? * * b/'; a='/*'; b=$(<<<$s tr -d "$a"); echo "$b"– mosvy
Dec 6 at 0:47
You should've left it at @Kusalananda's edit. The extra quotes you added are absolutely useless -- unlike those around
"$a" and "$b", they make no difference, no matter the value of string and a. Example: s='/b * .? * * b/'; a='/*'; b=$(<<<$s tr -d "$a"); echo "$b"– mosvy
Dec 6 at 0:47
@mosvy Yes, good point… I guess my thinking was that Kusalananda's were also not necessary in this case either. Admittedly
$b may well contain whitespace in another variant, but $a almost certainly would not (at least not in a way that would break). I agree that my quotes are even more useless, but I figured I'd use them for "good practice", in a general sense… which was likely Kusalananda's thinking? I've edited the question to point this out anyway.– Sparhawk
Dec 6 at 0:59
@mosvy Yes, good point… I guess my thinking was that Kusalananda's were also not necessary in this case either. Admittedly
$b may well contain whitespace in another variant, but $a almost certainly would not (at least not in a way that would break). I agree that my quotes are even more useless, but I figured I'd use them for "good practice", in a general sense… which was likely Kusalananda's thinking? I've edited the question to point this out anyway.– Sparhawk
Dec 6 at 0:59
the quotes around
"$a" and "$b" are not just "good practice" (ie cargo cult). Try my example without either of them and you will see that they really make a difference.– mosvy
Dec 6 at 1:02
the quotes around
"$a" and "$b" are not just "good practice" (ie cargo cult). Try my example without either of them and you will see that they really make a difference.– mosvy
Dec 6 at 1:02
@mosvy Ah yes okay. I forgot to use bash instead of my normal zsh. Yes, the
* causes problems. Hopefully my edit includes this interpretation.– Sparhawk
Dec 6 at 1:08
@mosvy Ah yes okay. I forgot to use bash instead of my normal zsh. Yes, the
* causes problems. Hopefully my edit includes this interpretation.– Sparhawk
Dec 6 at 1:08
add a comment |
up vote
6
down vote
No need to run external commands when using recent shells' "parameter expansion":
echo ${string//["$a"]}
AAA
answered Dec 4 at 11:28
RudiC
3,9541312
add a comment |
up vote
6
down vote
No need to run external commands when using recent shells' "parameter expansion":
echo ${string//["$a"]}
AAA
answered Dec 4 at 11:28
RudiC
3,9541312
add a comment |
up vote
6
down vote
up vote
6
down vote
No need to run external commands when using recent shells' "parameter expansion":
echo ${string//["$a"]}
AAA
answered Dec 4 at 11:28
RudiC
3,9541312
No need to run external commands when using recent shells' "parameter expansion":
echo ${string//["$a"]}
AAA
answered Dec 4 at 11:28
RudiC
3,9541312
edited Dec 4 at 12:06
answered Dec 4 at 11:28
RudiC
3,9541312
answered Dec 4 at 11:28
RudiC
3,9541312
answered Dec 4 at 11:28
RudiC
3,9541312
3,9541312
add a comment |
add a comment |
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please also keep in mind to quote your variable that you should. read Why does my shell script choke on whitespace or other special characters?.
– αғsнιη
Dec 4 at 12:17