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I didn't know of those functions. Never covered, as far as I remember, as I lunged to learn unix user environment back in the mid-late 1990's. The value of a peer group to be mentored into the power of the unix philosophy... A * run of shell commands... * "got it" with own versions of "true" and "false"? * "mytrue.sh" and "myfalse.sh" tested in the shell * some more trying shell commands bash-3.2$ false bash-3.2$ true bash-3.2$ if true; then echo y; else echo n; fi y bash-3.2$ if false; then echo y; else echo n; fi n "mytrue.sh": #!/bin/sh exit 0 "myfalse.sh": #!/bin/sh exit 1 bash-3.2$ if ./mytrue.sh; then echo y; else echo n; fi y bash-3.2$ if ./myfalse.sh; then echo y; else echo n; fi n bash-3.2$ if (true&&false); then echo y; else echo n; fi n bash-3.2$ if (true||false); then echo y; else echo n; fi y * Bit more reading => learned about shell "?" variable bash-3.2$ true; echo $? 0 bash-3.2$ false; echo $? 1 Been a delight to wake up to finding this. The unix way of thinking is rewarding. Best wishes, Rich Smith > On 19 Oct 2023, at 00:55, Simon Waters <simon@xxxxxxxxxxxxxx> wrote: > > Call that a trivial shell script. > > I have seen /bin/false implemented as a Bourne shell script. > > The implementation is left as an exercise to the reader. > > > -- > The Mailing List for the Devon & Cornwall LUG > FAQ: https://www.dcglug.org.uk/faq/ -- The Mailing List for the Devon & Cornwall LUG FAQ: https://www.dcglug.org.uk/faq/