Backup text file using date string

up vote
1
down vote

favorite

I am trying to append a date string to the file name to back up a text file

So I did:

cp "$infile" "$infile"_backup_ date +"%Y%m%d_%H%M%S"

But its not working, how can I append the output of "date" in a string?

user1@serv01:~/test_sh_append> date +"%Y%m%d_%H%M%S"
20171222_075003
user1@serv01:~/test_sh_append> echo date +"%Y%m%d_%H%M%S"
date +%Y%m%d_%H%M%S

edited Dec 22 '17 at 16:00

asked Dec 22 '17 at 15:55

user648026

1084

add a commentÂ |Â

up vote
1
down vote

favorite

I am trying to append a date string to the file name to back up a text file

So I did:

cp "$infile" "$infile"_backup_ date +"%Y%m%d_%H%M%S"

But its not working, how can I append the output of "date" in a string?

user1@serv01:~/test_sh_append> date +"%Y%m%d_%H%M%S"
20171222_075003
user1@serv01:~/test_sh_append> echo date +"%Y%m%d_%H%M%S"
date +%Y%m%d_%H%M%S

edited Dec 22 '17 at 16:00

asked Dec 22 '17 at 15:55

user648026

1084

add a commentÂ |Â

up vote
1
down vote

favorite

I am trying to append a date string to the file name to back up a text file

So I did:

cp "$infile" "$infile"_backup_ date +"%Y%m%d_%H%M%S"

But its not working, how can I append the output of "date" in a string?

user1@serv01:~/test_sh_append> date +"%Y%m%d_%H%M%S"
20171222_075003
user1@serv01:~/test_sh_append> echo date +"%Y%m%d_%H%M%S"
date +%Y%m%d_%H%M%S

edited Dec 22 '17 at 16:00

asked Dec 22 '17 at 15:55

user648026

1084

I am trying to append a date string to the file name to back up a text file

So I did:

cp "$infile" "$infile"_backup_ date +"%Y%m%d_%H%M%S"

But its not working, how can I append the output of "date" in a string?

user1@serv01:~/test_sh_append> date +"%Y%m%d_%H%M%S"
20171222_075003
user1@serv01:~/test_sh_append> echo date +"%Y%m%d_%H%M%S"
date +%Y%m%d_%H%M%S

edited Dec 22 '17 at 16:00

asked Dec 22 '17 at 15:55

user648026

1084

edited Dec 22 '17 at 16:00

asked Dec 22 '17 at 15:55

user648026

1084

asked Dec 22 '17 at 15:55

user648026

1084

asked Dec 22 '17 at 15:55

user648026

1084

add a commentÂ |Â

2 Answers
2

active

oldest

votes

up vote
3
down vote

accepted

Use the following:

cp "$infile" "$infile_backup_"$(date +"%Y%m%d_%H%M%S")

$infile - variable $infile interpolated within concatenated string

$(date +"%Y%m%d_%H%M%S") - command substitution, the output of which becomes the ending part of the resulting concatenated string (new filename)

If the date format specifier would contain whitespace(s) like %Y%m%d %H%M%S - wrap the entire concatenated sequence with double quotes "$infile_backup_$(date +"%Y%m%d %H%M%S")"

edited Dec 23 '17 at 8:49

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

Thank you! This works! can you explain the magic?
â€“Â user648026
Dec 22 '17 at 16:06

@user648026, yes, see the explanation
â€“Â RomanPerekhrest
Dec 22 '17 at 16:09

+1. But...while this is safe enough with this date command using that format string, as a general rule it is better to wrap the entire string in double quotes. e.g. "$infile_backup_$(date +"%Y%m%d_%H%M%S")". This works correctly even though it looks like the double-quotes are nested, because the $(date...) is in a completely new/separate quoting context. If the format contained any whitespace characters or other shell metacharacters then quoting it as I've mentioned would be required.
â€“Â cas
Dec 23 '17 at 6:07

@cas, ok, added notation
â€“Â RomanPerekhrest
Dec 23 '17 at 8:49

1

You might want cp -p instead of plain cp to preserve the metadata such as timestamps and permissions.
â€“Â roaima
Dec 23 '17 at 15:11

add a commentÂ |Â

up vote
1
down vote

I have done by below method

i=`date +%Y%m%d_%H%M%S`; cp inputfile inputfile_$i

where i is variable which contains date command output

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

add a commentÂ |Â

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

up vote
3
down vote

accepted

Use the following:

cp "$infile" "$infile_backup_"$(date +"%Y%m%d_%H%M%S")

$infile - variable $infile interpolated within concatenated string

$(date +"%Y%m%d_%H%M%S") - command substitution, the output of which becomes the ending part of the resulting concatenated string (new filename)

If the date format specifier would contain whitespace(s) like %Y%m%d %H%M%S - wrap the entire concatenated sequence with double quotes "$infile_backup_$(date +"%Y%m%d %H%M%S")"

edited Dec 23 '17 at 8:49

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

Thank you! This works! can you explain the magic?
â€“Â user648026
Dec 22 '17 at 16:06

@user648026, yes, see the explanation
â€“Â RomanPerekhrest
Dec 22 '17 at 16:09

+1. But...while this is safe enough with this date command using that format string, as a general rule it is better to wrap the entire string in double quotes. e.g. "$infile_backup_$(date +"%Y%m%d_%H%M%S")". This works correctly even though it looks like the double-quotes are nested, because the $(date...) is in a completely new/separate quoting context. If the format contained any whitespace characters or other shell metacharacters then quoting it as I've mentioned would be required.
â€“Â cas
Dec 23 '17 at 6:07

@cas, ok, added notation
â€“Â RomanPerekhrest
Dec 23 '17 at 8:49

1

You might want cp -p instead of plain cp to preserve the metadata such as timestamps and permissions.
â€“Â roaima
Dec 23 '17 at 15:11

add a commentÂ |Â

up vote
3
down vote

accepted

Use the following:

cp "$infile" "$infile_backup_"$(date +"%Y%m%d_%H%M%S")

$infile - variable $infile interpolated within concatenated string

$(date +"%Y%m%d_%H%M%S") - command substitution, the output of which becomes the ending part of the resulting concatenated string (new filename)

If the date format specifier would contain whitespace(s) like %Y%m%d %H%M%S - wrap the entire concatenated sequence with double quotes "$infile_backup_$(date +"%Y%m%d %H%M%S")"

edited Dec 23 '17 at 8:49

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

Thank you! This works! can you explain the magic?
â€“Â user648026
Dec 22 '17 at 16:06

@user648026, yes, see the explanation
â€“Â RomanPerekhrest
Dec 22 '17 at 16:09

+1. But...while this is safe enough with this date command using that format string, as a general rule it is better to wrap the entire string in double quotes. e.g. "$infile_backup_$(date +"%Y%m%d_%H%M%S")". This works correctly even though it looks like the double-quotes are nested, because the $(date...) is in a completely new/separate quoting context. If the format contained any whitespace characters or other shell metacharacters then quoting it as I've mentioned would be required.
â€“Â cas
Dec 23 '17 at 6:07

@cas, ok, added notation
â€“Â RomanPerekhrest
Dec 23 '17 at 8:49

1

You might want cp -p instead of plain cp to preserve the metadata such as timestamps and permissions.
â€“Â roaima
Dec 23 '17 at 15:11

add a commentÂ |Â

up vote
3
down vote

accepted

Use the following:

cp "$infile" "$infile_backup_"$(date +"%Y%m%d_%H%M%S")

$infile - variable $infile interpolated within concatenated string

$(date +"%Y%m%d_%H%M%S") - command substitution, the output of which becomes the ending part of the resulting concatenated string (new filename)

If the date format specifier would contain whitespace(s) like %Y%m%d %H%M%S - wrap the entire concatenated sequence with double quotes "$infile_backup_$(date +"%Y%m%d %H%M%S")"

edited Dec 23 '17 at 8:49

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

Use the following:

cp "$infile" "$infile_backup_"$(date +"%Y%m%d_%H%M%S")

$infile - variable $infile interpolated within concatenated string

$(date +"%Y%m%d_%H%M%S") - command substitution, the output of which becomes the ending part of the resulting concatenated string (new filename)

If the date format specifier would contain whitespace(s) like %Y%m%d %H%M%S - wrap the entire concatenated sequence with double quotes "$infile_backup_$(date +"%Y%m%d %H%M%S")"

edited Dec 23 '17 at 8:49

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

edited Dec 23 '17 at 8:49

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

answered Dec 22 '17 at 16:00

RomanPerekhrest

22.4k12145

Thank you! This works! can you explain the magic?
â€“Â user648026
Dec 22 '17 at 16:06

@user648026, yes, see the explanation
â€“Â RomanPerekhrest
Dec 22 '17 at 16:09

+1. But...while this is safe enough with this date command using that format string, as a general rule it is better to wrap the entire string in double quotes. e.g. "$infile_backup_$(date +"%Y%m%d_%H%M%S")". This works correctly even though it looks like the double-quotes are nested, because the $(date...) is in a completely new/separate quoting context. If the format contained any whitespace characters or other shell metacharacters then quoting it as I've mentioned would be required.
â€“Â cas
Dec 23 '17 at 6:07

@cas, ok, added notation
â€“Â RomanPerekhrest
Dec 23 '17 at 8:49

1

You might want cp -p instead of plain cp to preserve the metadata such as timestamps and permissions.
â€“Â roaima
Dec 23 '17 at 15:11

add a commentÂ |Â

Thank you! This works! can you explain the magic?
â€“Â user648026
Dec 22 '17 at 16:06

@user648026, yes, see the explanation
â€“Â RomanPerekhrest
Dec 22 '17 at 16:09

+1. But...while this is safe enough with this date command using that format string, as a general rule it is better to wrap the entire string in double quotes. e.g. "$infile_backup_$(date +"%Y%m%d_%H%M%S")". This works correctly even though it looks like the double-quotes are nested, because the $(date...) is in a completely new/separate quoting context. If the format contained any whitespace characters or other shell metacharacters then quoting it as I've mentioned would be required.
â€“Â cas
Dec 23 '17 at 6:07

@cas, ok, added notation
â€“Â RomanPerekhrest
Dec 23 '17 at 8:49

1

You might want cp -p instead of plain cp to preserve the metadata such as timestamps and permissions.
â€“Â roaima
Dec 23 '17 at 15:11

Thank you! This works! can you explain the magic?
â€“Â user648026
Dec 22 '17 at 16:06

@user648026, yes, see the explanation
â€“Â RomanPerekhrest
Dec 22 '17 at 16:09

+1. But...while this is safe enough with this date command using that format string, as a general rule it is better to wrap the entire string in double quotes. e.g. "$infile_backup_$(date +"%Y%m%d_%H%M%S")". This works correctly even though it looks like the double-quotes are nested, because the $(date...) is in a completely new/separate quoting context. If the format contained any whitespace characters or other shell metacharacters then quoting it as I've mentioned would be required.
â€“Â cas
Dec 23 '17 at 6:07

@cas, ok, added notation
â€“Â RomanPerekhrest
Dec 23 '17 at 8:49

You might want cp -p instead of plain cp to preserve the metadata such as timestamps and permissions.
â€“Â roaima
Dec 23 '17 at 15:11

add a commentÂ |Â

up vote
1
down vote

I have done by below method

i=`date +%Y%m%d_%H%M%S`; cp inputfile inputfile_$i

where i is variable which contains date command output

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

add a commentÂ |Â

up vote
1
down vote

I have done by below method

i=`date +%Y%m%d_%H%M%S`; cp inputfile inputfile_$i

where i is variable which contains date command output

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

add a commentÂ |Â

up vote
1
down vote

I have done by below method

i=`date +%Y%m%d_%H%M%S`; cp inputfile inputfile_$i

where i is variable which contains date command output

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

I have done by below method

i=`date +%Y%m%d_%H%M%S`; cp inputfile inputfile_$i

where i is variable which contains date command output

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

answered Dec 23 '17 at 8:42

Praveen Kumar BS

1,010128

add a commentÂ |Â

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