How to echo shell commands as they are executed

Question

In a shell script  how do I echo all shell commands called and expand any variable names   For example  given the following line   ls  DIRNAME   I would like the script to run the command and display the following  ls  full path to some dir   The purpose is to save a log of all shell commands called and their arguments  Is there perhaps a better way of generating such a log

User · Answer

You can execute a Bash script in debug mode with the -x option   This will echo all the commands   bash -x example script sh    Console output   cd  home user   mv text txt mytext txt   You can also save the -x option in the script  Just specify the -x option in the shebang            example script sh                        bin bash -x  cd  home user mv text txt mytext txt                                                    example script sh    Console output   cd  home user   mv text txt mytext txt

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set -x will give you what you want   Here is an example shell script to demonstrate      bin bash set -x  echo on  ls  PWD   This expands all variables and prints the full commands before output of the command   Output     ls  home user  file1 txt file2 txt

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You can also toggle this for select lines in your script by wrapping them in set -x and set  x  for example      bin bash     if      -e  OUT FILE     then    echo  grabbing  URL     set -x    curl --fail --noproxy  SERV -s -S  URL -o  OUT FILE    set  x fi

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set -x or set -o xtrace expands variables and prints a little   sign before the line   set -v or set -o verbose does not expand the variables before printing   Use set  x and set  v to turn off the above settings   On the first line of the script  one can put    bin sh -x  or -v  to have the same effect as set -x  or -v  later in the script   The above also works with  bin sh   See the bash-hackers  wiki on set attributes  and on debugging     cat shl    bin bash                                                                       DIR  tmp so ls  DIR    bash -x shl    DIR  tmp so   ls  tmp so

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I use a function to echo and run the command      bin bash   Function to display commands exe     echo                     exe echo hello world   Which outputs    echo hello world hello world   For more complicated commands pipes  etc   you can use eval      bin bash   Function to display commands exe     echo         eval                exe eval  echo  Hello  World     cut -d     -f1    Which outputs     echo  Hello  World     cut -d     -f1 Hello

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For csh and tcsh  you can set verbose or set echo  or you can even set both  but it may result in some duplication most of the time    The verbose option prints pretty much the exact shell expression that you type   The echo option is more indicative of what will be executed through spawning     http   www tcsh org tcsh html Special shell variables html verbose  http   www tcsh org tcsh html Special shell variables html echo    Special shell variables  verbose     If set  causes the words of each command to be printed  after history substitution  if any   Set by the -v command line option   echo     If set  each command with its arguments is echoed just before it is executed  For non-builtin commands all expansions occur before echoing  Builtin commands are echoed before command and filename substitution  because these substitutions are then done selectively  Set by the -x command line option

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Another option is to put  -x  at the top of your script instead of on the command line     cat   server    bin bash -x ssh user server      server   ssh user server user server s password   C

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According to TLDP s Bash Guide for Beginners  Chapter 2  Writing and debugging scripts      2 3 1  Debugging on the entire script    bash -x script1 sh                There is now a full-fledged debugger for Bash  available at SourceForge  These debugging features are available in most modern versions of Bash  starting from 3 x       2 3 2  Debugging on part s  of the script  set -x              Activate debugging from here w set  x              Stop debugging from here                Table 2-1  Overview of set debugging options       Short    Long notation   Result     ------- --------------- --------------------------------------------------------------     set -f   set -o noglob   Disable file name generation using metacharacters  globbing       set -v   set -o verbose  Prints shell input lines as they are read      set -x   set -o xtrace   Print command traces before executing command                Alternatively  these modes can be specified in the script itself  by   adding the desired options to the first line shell declaration    Options can be combined  as is usually the case with UNIX commands      bin bash -xv

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Combining all the answers I found this to be the best exe        set -x      quot    quot        set  x    2 gt  dev null     example exe go generate          set  x    2 gt  dev null from https   stackoverflow com a 19226038 8608146

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To allow for compound commands to be echoed  I use eval plus Soth s exe function to echo and run the command  This is useful for piped commands that would otherwise only show none or just the initial part of the piped command   Without eval   exe     echo                    exe ls -F   grep   txt   Outputs     file txt   With eval   exe     echo                    exe eval  ls -F   grep   txt    Which outputs    exe eval  ls -F   grep   txt  file txt

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For zsh  echo  setopt VERBOSE   And for debugging   setopt XTRACE

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Type  bash -x  on the command line before the name of the Bash script  For instance  to execute foo sh  type   bash -x foo sh

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cat exampleScript sh    bin bash name  karthik   echo  name   bash -x exampleScript sh   Output is as follows

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shuckc s answer for echoing select lines has a few downsides  you end up with the following set  x command being echoed as well  and you lose the ability to test the exit code with    since it gets overwritten by the set  x   Another option is to run the command in a subshell   echo  getting URL       set -x   curl -s --fail  URL -o  OUTFILE    if      -eq 0     then     echo  curl failed      exit 1 fi   which will give you output like   getting URL      curl -s --fail http   example com missing -o  tmp example curl failed   This does incur the overhead of creating a new subshell for the command  though

[bash] How to echo shell commands as they are executed

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