Accidents with `echo >` and `echo >>`











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Today I learned the distinction between echo > and echo >> when I overwrote my log file. I don't trust myself and know I'll make this mistake again unless I make this idiot proof. Is there a way to do this?






bash append overwrite io-redirection







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  • 1




    Practice, more practice, and yet more practice — and don't write I/O redirections without thinking what you mean. Beware of using set -o noclobber and then using >! extravagantly; that defeats the objective.
    – Jonathan Leffler
    Nov 10 at 17:32








  • 1




    noclobber is a way, but it might cause bigger accidents in the future: When you trust the safety belt in your own environment and want to help a colleague (or on another system or as root), you start overwriting files again.
    – Walter A
    Nov 10 at 21:32















up vote
1
down vote

favorite












Today I learned the distinction between echo > and echo >> when I overwrote my log file. I don't trust myself and know I'll make this mistake again unless I make this idiot proof. Is there a way to do this?






bash append overwrite io-redirection







share|improve this question




















  • 1




    Practice, more practice, and yet more practice — and don't write I/O redirections without thinking what you mean. Beware of using set -o noclobber and then using >! extravagantly; that defeats the objective.
    – Jonathan Leffler
    Nov 10 at 17:32








  • 1




    noclobber is a way, but it might cause bigger accidents in the future: When you trust the safety belt in your own environment and want to help a colleague (or on another system or as root), you start overwriting files again.
    – Walter A
    Nov 10 at 21:32













up vote
1
down vote

favorite









up vote
1
down vote

favorite











Today I learned the distinction between echo > and echo >> when I overwrote my log file. I don't trust myself and know I'll make this mistake again unless I make this idiot proof. Is there a way to do this?






bash append overwrite io-redirection







share|improve this question















Today I learned the distinction between echo > and echo >> when I overwrote my log file. I don't trust myself and know I'll make this mistake again unless I make this idiot proof. Is there a way to do this?






bash append overwrite io-redirection




bash append overwrite io-redirection






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 10 at 17:50









Cyrus

44.2k43375




44.2k43375










asked Nov 10 at 17:23









Patrick Stetz

10016




10016








  • 1




    Practice, more practice, and yet more practice — and don't write I/O redirections without thinking what you mean. Beware of using set -o noclobber and then using >! extravagantly; that defeats the objective.
    – Jonathan Leffler
    Nov 10 at 17:32








  • 1




    noclobber is a way, but it might cause bigger accidents in the future: When you trust the safety belt in your own environment and want to help a colleague (or on another system or as root), you start overwriting files again.
    – Walter A
    Nov 10 at 21:32














  • 1




    Practice, more practice, and yet more practice — and don't write I/O redirections without thinking what you mean. Beware of using set -o noclobber and then using >! extravagantly; that defeats the objective.
    – Jonathan Leffler
    Nov 10 at 17:32








  • 1




    noclobber is a way, but it might cause bigger accidents in the future: When you trust the safety belt in your own environment and want to help a colleague (or on another system or as root), you start overwriting files again.
    – Walter A
    Nov 10 at 21:32








1




1




Practice, more practice, and yet more practice — and don't write I/O redirections without thinking what you mean. Beware of using set -o noclobber and then using >! extravagantly; that defeats the objective.
– Jonathan Leffler
Nov 10 at 17:32






Practice, more practice, and yet more practice — and don't write I/O redirections without thinking what you mean. Beware of using set -o noclobber and then using >! extravagantly; that defeats the objective.
– Jonathan Leffler
Nov 10 at 17:32






1




1




noclobber is a way, but it might cause bigger accidents in the future: When you trust the safety belt in your own environment and want to help a colleague (or on another system or as root), you start overwriting files again.
– Walter A
Nov 10 at 21:32




noclobber is a way, but it might cause bigger accidents in the future: When you trust the safety belt in your own environment and want to help a colleague (or on another system or as root), you start overwriting files again.
– Walter A
Nov 10 at 21:32












1 Answer
1






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up vote
4
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Open your ~/.bashrc file and put set -o noclobber at the end.



Now whenever echo > is called on an existing file, the file will not be overwritten and an error will appear saying: -bash: FILENAME: cannot overwrite existing file.



Remember to do source ~/.bashrc for these changes to take effect!






share|improve this answer

















  • 1




    You might note that if you have noclobber set, doing "echo 123 > xyz; echo 456 > xyz" will generate an error on the second, as intended. However, sometimes you need to override it. Obviously, you can use unset noclobber; echo 456 > xyz; set -o noclobber, but you can also use echo 456 >! xyz. Be cautious though — if you find yourself routinely writing >!, then the noclobber really isn't helping and you need to think accurately when working.
    – Jonathan Leffler
    Nov 10 at 17:31











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up vote
4
down vote













Open your ~/.bashrc file and put set -o noclobber at the end.



Now whenever echo > is called on an existing file, the file will not be overwritten and an error will appear saying: -bash: FILENAME: cannot overwrite existing file.



Remember to do source ~/.bashrc for these changes to take effect!






share|improve this answer

















  • 1




    You might note that if you have noclobber set, doing "echo 123 > xyz; echo 456 > xyz" will generate an error on the second, as intended. However, sometimes you need to override it. Obviously, you can use unset noclobber; echo 456 > xyz; set -o noclobber, but you can also use echo 456 >! xyz. Be cautious though — if you find yourself routinely writing >!, then the noclobber really isn't helping and you need to think accurately when working.
    – Jonathan Leffler
    Nov 10 at 17:31















up vote
4
down vote













Open your ~/.bashrc file and put set -o noclobber at the end.



Now whenever echo > is called on an existing file, the file will not be overwritten and an error will appear saying: -bash: FILENAME: cannot overwrite existing file.



Remember to do source ~/.bashrc for these changes to take effect!






share|improve this answer

















  • 1




    You might note that if you have noclobber set, doing "echo 123 > xyz; echo 456 > xyz" will generate an error on the second, as intended. However, sometimes you need to override it. Obviously, you can use unset noclobber; echo 456 > xyz; set -o noclobber, but you can also use echo 456 >! xyz. Be cautious though — if you find yourself routinely writing >!, then the noclobber really isn't helping and you need to think accurately when working.
    – Jonathan Leffler
    Nov 10 at 17:31













up vote
4
down vote










up vote
4
down vote









Open your ~/.bashrc file and put set -o noclobber at the end.



Now whenever echo > is called on an existing file, the file will not be overwritten and an error will appear saying: -bash: FILENAME: cannot overwrite existing file.



Remember to do source ~/.bashrc for these changes to take effect!






share|improve this answer












Open your ~/.bashrc file and put set -o noclobber at the end.



Now whenever echo > is called on an existing file, the file will not be overwritten and an error will appear saying: -bash: FILENAME: cannot overwrite existing file.



Remember to do source ~/.bashrc for these changes to take effect!







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 10 at 17:23









Patrick Stetz

10016




10016








  • 1




    You might note that if you have noclobber set, doing "echo 123 > xyz; echo 456 > xyz" will generate an error on the second, as intended. However, sometimes you need to override it. Obviously, you can use unset noclobber; echo 456 > xyz; set -o noclobber, but you can also use echo 456 >! xyz. Be cautious though — if you find yourself routinely writing >!, then the noclobber really isn't helping and you need to think accurately when working.
    – Jonathan Leffler
    Nov 10 at 17:31














  • 1




    You might note that if you have noclobber set, doing "echo 123 > xyz; echo 456 > xyz" will generate an error on the second, as intended. However, sometimes you need to override it. Obviously, you can use unset noclobber; echo 456 > xyz; set -o noclobber, but you can also use echo 456 >! xyz. Be cautious though — if you find yourself routinely writing >!, then the noclobber really isn't helping and you need to think accurately when working.
    – Jonathan Leffler
    Nov 10 at 17:31








1




1




You might note that if you have noclobber set, doing "echo 123 > xyz; echo 456 > xyz" will generate an error on the second, as intended. However, sometimes you need to override it. Obviously, you can use unset noclobber; echo 456 > xyz; set -o noclobber, but you can also use echo 456 >! xyz. Be cautious though — if you find yourself routinely writing >!, then the noclobber really isn't helping and you need to think accurately when working.
– Jonathan Leffler
Nov 10 at 17:31




You might note that if you have noclobber set, doing "echo 123 > xyz; echo 456 > xyz" will generate an error on the second, as intended. However, sometimes you need to override it. Obviously, you can use unset noclobber; echo 456 > xyz; set -o noclobber, but you can also use echo 456 >! xyz. Be cautious though — if you find yourself routinely writing >!, then the noclobber really isn't helping and you need to think accurately when working.
– Jonathan Leffler
Nov 10 at 17:31


















 

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