Padding characters in printf

Question

I am writing a bash shell script to display if a process is running or not   So far  I got this   printf   -50s  s n   PROC NAME  UP    The code gives me this output   JBoss                                               DOWN   GlassFish                                           UP   verylongprocessname                                 UP    I want to pad the gap between the two fields with a  -  or     to make it more readable  How do I do that without disturbing the alignment of the fields   The output I want is   JBoss -------------------------------------------   DOWN   GlassFish ---------------------------------------   UP   verylongprocessname -----------------------------   UP

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Pure Bash  no external utilities  This demonstration does full justification  but you can just omit subtracting the length of the second string if you want ragged-right lines   pad   printf   0 1s   -  1  60   padlength 40 string2  bbbbbbb  for string1 in a aa aaaa aaaaaaaa do      printf   s    string1       printf      s  0    padlength -    string1  -    string2       pad       printf   s n    string2       string2   string2 1  done   Unfortunately  in that technique  the length of the pad string has to be hardcoded to be longer than the longest one you think you ll need  but the padlength can be a variable as shown  However  you can replace the first line with these three to be able to use a variable for the length of the pad   padlimit 60 pad   printf    s    padlimit   pad   pad    -    So the pad  padlimit and padlength  could be based on terminal width   COLUMNS  or computed from the length of the longest data string   Output   a--------------------------------bbbbbbb aa--------------------------------bbbbbb aaaa-------------------------------bbbbb aaaaaaaa----------------------------bbbb   Without subtracting the length of the second string   a---------------------------------------bbbbbbb aa--------------------------------------bbbbbb aaaa------------------------------------bbbbb aaaaaaaa--------------------------------bbbb   The first line could instead be the equivalent  similar to sprintf    printf -v pad   0 1s   -  1  60    or similarly for the more dynamic technique   printf -v pad    s    padlimit    You can do the printing all on one line if you prefer   printf   s    s s n    string1  0    padlength -    string1  -    string2       pad    string2

User · Answer

There s no way to pad with anything but spaces using printf  You can use sed   printf   -50s  s n   PROC NAME  UP    sed -e  s   - g  -e  s       -e  s -

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If you are ending the pad characters at some fixed column number  then you can overpad and cut to length     Previously defined    PROC NAME   PROC STATUS  PAD  --------------------------------------------------  LINE   printf   s  s    PROC NAME    PAD    cut -c 1-   PAD   printf   s  s n    LINE    PROC STATUS

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Trivial  but working  solution   echo -e  ----------------------------  UP  r PROC NAME

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This one is even simpler and execs no external commands     PROC NAME  JBoss    PROC STATUS  UP    printf   - 20s   s  n     PROC NAME                                     PROC STATUS   JBoss                 UP

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I think this is the simplest solution  Pure shell builtins  no inline math  It borrows from previous answers   Just substrings and the         meta-variable   A    gt --------------------- lt        Strip excess padding from the right    B  A very long header   echo    A 0 -   B    B  B  shrt hdr             echo    A 0 -   B    B    Produces    gt ----- A very long header   gt --------------- shrt hdr     Strip excess padding from the left    B  A very long header   echo    A    B    B  B  shrt hdr             echo    A    B    B    Produces  ----- lt   A very long header --------------- lt   shrt hdr

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echo -n   PROC NAME   printf   055  0s   1  40      head -c 40   echo -n    UP     Explanation    printf   055  0s   1  40  - Create 40 dashes  dash is interpreted as option so use escaped ascii code instead    PROC NAME      - Concatenate  PROC NAME and dashes   head -c 40 - Trim string to first 40 chars

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using echo only  The anwser of  Dennis Williamson is working just fine except I was trying to do this using echo  Echo allows to output charcacters with a certain color  Using printf would remove that coloring and print unreadable characters  Here s the echo-only alternative   string1 abc string2 123456 echo -en   string1   for   i 0  i lt   25 -    string1    i      echo -n  -     echo -e    string2    output    abc ---------------------- 123456   of course you can use all the variations proposed by  Dennis Williamson whether you want the right part to be left- or right-aligned  replacing 25 -    string1  by 25 -    string1  -    string2  etc

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Simple Console Span Fill Pad Padding with automatic scaling resizing Method and Example   function create-console-spanner           1  left-side-text  2  right-side-text     local spanner         eval printf -v spanner     0 1s     -  1      tput cols - 2 -    1  -    2        printf   s  s  s    1    spanner    2       Example  create-console-spanner  loading graphics module    success    Now here is a full-featured-color-character-terminal-suite that does everything in regards to printing a color and style formatted string with a spanner     Author  Triston J  Taylor  lt pc wiz tt gmail com gt    Date  Friday  October 19th  2018   License  OPEN-SOURCE ANY  NO-PRODUCT-LIABILITY OR WARRANTIES    Title  paint sh   Description  color character terminal driver controller suite  declare -A PAINT   none   tput sgr0   bold   tput bold   black   tput setaf 0   red   tput setaf 1   green   tput setaf 2   yellow   tput setaf 3   blue   tput setaf 4   magenta   tput setaf 5   cyan   tput setaf 6   white   tput setaf 7     declare -i PAINT ACTIVE 1   function paint-replace         local contents   cat      echo    contents   1  2      source  lt  cat  lt  lt EOF function paint-activate         echo           for k in    PAINT      do echo -n paint-replace     amp  k          PAINT  k         done  cat    EOF    source  lt  cat  lt  lt EOF function paint-deactivate        echo           for k in    PAINT      do echo -n paint-replace     amp  k              done  cat        EOF    function paint-get-spanner                  0     amp  amp  set -- - 0      declare -i l      tput cols  -   2        eval printf     0 1s       1 0 1   1   l     function paint-span         local left format  1 right format  3     local left length   paint-format -l   left format   right length   paint-format -l   right format       paint-format   left format       paint-get-spanner   2      left length   right length        paint-format   right format      function paint-format         local VAR    OPTIONS         local -i MODE 0 PRINT FILE 0 PRINT VAR 1 PRINT SIZE 2      while       1 0 2       - vl       do         if      1      -v      then OPTIONS   -v  2   MODE  PRINT VAR  shift 2  continue  fi          if      1      -l      then OPTIONS   -v VAR   MODE  PRINT SIZE  shift 1  continue  fi      done      OPTIONS    --      local format   1   shift      if    MODE    PRINT SIZE  amp  amp  PAINT ACTIVE     then         format   paint-activate   format amp none        else         format   paint-deactivate   format       fi     printf  OPTIONS    format                MODE    PRINT SIZE     amp  amp  printf   i n      VAR      true     function paint-show-pallette         local -i PAINT ACTIVE 1     paint-format  Normal   amp red red  amp green green  amp blue blue  amp magenta magenta  amp yellow yellow  amp cyan cyan  amp white white  amp black black n       paint-format    Bold   amp bold  amp red red  amp green green  amp blue blue  amp magenta magenta  amp yellow yellow  amp cyan cyan  amp white white  amp black black n       To print a color  that s simple enough  paint-format   amp red This is  s n  red And you might want to get bold later on  paint-format   amp bold  s  n  WOW  The -l option to the paint-format function measures the text so you can do console font metrics operations   The -v option to the paint-format function works the same as printf but cannot be supplied with -l  Now for the spanning   paint-span  hello        amp blue world   note  we didn t add newline terminal sequence  but the text fills the terminal  so the next line only appears to be a newline terminal sequence   and the output of that is   hello                               world

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Here s another one       echo JBoss DOWN  echo GlassFish UP      while read PROC STATUS  do echo -n   PROC    printf      48-   PROC   s     tr     -  echo     STATUS    done JBoss --------------------------------------------  DOWN  GlassFish ----------------------------------------  UP

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Pure Bash  Use the length of the value of  PROC NAME  as offset for the fixed string  line     line  ----------------------------------------  PROC NAME  abc  printf   s  s  UP  n   PROC NAME    line    PROC NAME    PROC NAME  abcdef  printf   s  s  UP  n   PROC NAME    line    PROC NAME      This gives  abc -------------------------------------  UP  abcdef ----------------------------------  UP

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Simple but it does work   printf   -50s s n    PROC NAME       STATUS     tr       -     Example of usage   while read PROC NAME STATUS  do       printf   -50s s n    PROC NAME       STATUS     tr       -   done  lt  lt  EOT  JBoss DOWN GlassFish UP VeryLongProcessName UP EOT   Output to stdout   JBoss --------------------------------------------  DOWN  GlassFish ----------------------------------------  UP  VeryLongProcessName ------------------------------  UP

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Bash   seq to allow parameter expansion  Similar to  Dennis Williamson answer  but if seq is available  the length of the pad string need not be hardcoded  The following code allows for passing a variable to the script as a positional parameter   COLUMNS    COLUMNS  80   padlength    1 - COLUMNS   pad   printf   x2D  0s    seq   padlength      string2  bbbbbbb  for string1 in a aa aaaa aaaaaaaa do      printf   s    string1       printf      s  0      padlength  -     string1   -     string2        pad       printf   s n    string2       string2   string2 1  done   The ASCII code  2D  is used instead of the character  -  to avoid the shell interpreting it as a command flag  Another option is  3D  to use       In absence of any padlength passed as an argument  the code above defaults to the 80 character standard terminal width   To take advantage of the the bash shell variable COLUMNS  i e   the width of the current terminal   the environment variable would need to be available to the script  One way is to source all the environment variables by executing the script preceded by     dot  command   like this      path to script   or  better  explicitly pass the COLUMNS variable when executing  like this    path to script  COLUMNS

[bash] Padding characters in printf

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